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Terra Mission (EOS/AM-1)

Spacecraft     Launch    Mission Status     Sensor Complement    EOS    References

Terra (formerly known as EOS/AM-1) is a joint Earth observing mission within NASA's ESE (Earth Science Enterprise) program between the United States, Japan, and Canada. The US provided the spacecraft, the launch, and three instruments developed by NASA (CERES, MISR, MODIS). Japan provided ASTER and Canada MOPITT. The Terra spacecraft is considered the flagship of NASA's EOS (Earth Observing Satellite) program. In February 1999, the EOS/AM-1 satellite was renamed by NASA to “Terra”. 1) 2) 3) 4)

The objective of the mission is to obtain information about the physical and radiative properties of clouds (ASTER, CERES, MISR, MODIS); air-land and air-sea exchanges of energy, carbon, and water (ASTER, MISR, MODIS); measurements of trace gases (MOPITT); and volcanology (ASTER, MISR, MODIS). The science objectives are:

• To provide the first global and seasonal measurements of the Earth system, including such critical functions as biological productivity of the land and oceans, snow and ice, surface temperature, clouds, water vapor, and land cover;

• To improve the ability to detect human impacts on the Earth system and climate, identify the “fingerprint” of human activity on climate, and predict climate change by using the new global observations in climate models;

• To help develop technologies for disaster prediction, characterization, and risk reduction from wildfires, volcanoes, floods, and droughts

• To start long-term monitoring of global climate change and environmental change.

Complemented by aircraft and ground-based measurements, Terra data will enable scientists to distinguish between natural and human-induced changes.

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Figure 1: Illustration of the Terra spacecraft (image credit: NASA)

Spacecraft:

Terra consists of a spacecraft bus built by Lockheed Martin Missiles and Space (LMMS) in Valley Forge, PA. The spacecraft is constructed with a truss-like primary structure built of graphite-epoxy tubular members. This lightweight structure provides the strength and stiffness needed to support the spacecraft throughout its various mission phases. The zenith face of the spacecraft is populated with equipment modules (EMs) housing the various spacecraft bus components. The EMs are sized and partitioned to facilitate pre-launch integration and test of the spacecraft.

EPS (Electrical Power Subsystem): A large single-wing solar array (size of 9 m x 5 m = 45 m2), deployed on the sunlit side of the spacecraft, maximizes both its power generation capability and the cold-space FOV (Field of View) available to instrument and equipment module radiators. The average power of the satellite is 2.53 kW provided by a GaAs/Ge solar array (max of 7.5 kW @ 120 V at BOL). The solar array is based on on a prototype lightweight flexible blanket solar array technology developed by TRW (use of single-junction GaAs/Ge photovoltaics). A coilable mast is used for the deployment of the solar array. The Terra spacecraft represents the first orbiting application of a 120 VDC high voltage spacecraft electrical power system implemented by NASA. A PDU (Power Distribution Unit) has been designed to provide 120 DC (±4%) under any load conditions. This regulated voltage, in turn, is achieved via a sequential shunt unit (SSU) and the 2 BCDUs. A NiH2 (nickel hydrogen) battery is used (54 cells series connected) to provide power during eclipse phases of the orbit. 5) 6) 7)

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Figure 2: Coilable mast deployer for the Terra solar array (image credit: NASA)

GN&C (Guidance Navigation and Control) subsystem: Terra is a three-axis stabilized design with a single rotating solar array. The GN&C subsystem is made up of sensors, actuators, an ACE (Attitude Control Electronics) unit, and software. A three-channel IRU (Inertial Reference Unit) determines body rates in all control modes. Solid-state star trackers provide fine attitude updates, processed by a Kalman filter to maintain precise 3-axis inertial knowledge. A 3-axis magnetometer senses the Earth's geomagnetic field, primarily for magnetic unloading of reaction wheels, but also as a sensor to determine an attitude failure during a deep space calibration maneuver. 8)

The backup sensors include an ESA (Earth Sensor Assembly) for roll and pitch sensing, and coarse sun sensors for pitch and yaw sensing of the sun line relative to the solar array. A fine sun sensor is used in the event that one star tracker fails or during the backup stellar acquisition mode. In addition to these sensors, a gyro-compassing computation is performed for backup yaw attitude determination.

A reaction wheel assembly provides primary attitude control. During normal mode, a wheel speed controller is available to bias the wheel speeds at a range that avoids zero rpm crossings (stagnation point). Magnetic torquer rods regulate the wheel momentum to < 25% capacity in four-wheel mode and < 50% capacity in the three-wheel mode (backup mode). Thrusters are used for attitude control during all velocity change maneuvers and for backup attitude control and wheel momentum unloading.

GN&C is a fault-tolerant system that includes an FDIR (Fault Detection, Isolation and Recovery) capability unique to each of the different operational control modes. If an attitude fault is detected, FDIR transfers all control functions to the ACE unit configured to use all redundant hardware. Once in safe mode, FDIR is disabled.

Sensor component

Units

Manufacturer/model

Mission heritage

Solid State Star Tracker (SSST)

2

BATC / CT-601

MSX, XTE

Earth Sensor Assembly) (ESA)

2

Ithaco / conical scanning

UARS

Coarse Sun Sensor (CSS)

2

Adcole / 42060

UARS

Fine Sun Sensor (FSS)

1

Adcole / 42070

TOPEX

Three Axis Magnetometer (TAM)

2

NASA/GSFC

EUVE, UARS

Inertial Reference Unit (IRU)

2

Kearfott / SKIRU-DII

XTE

 

 

 

 

Actuator component

Units

Manufacturer/model

Heritage

Reaction Wheel Assembly (RWA)

4

Honeywell / EOS-AM

Similar to EUVE

Magnetic Torquer Rod (MTR)

3

Ithaco / TR500CFR

EUVE

Attitude Control Thruster

6 (x 2)

Olin Aerospace (Primex)

 

Delta-v thruster

2 (x 2)

Olin Aerospace (Primex)

 

Table 1: Overview of GN&C sensors and actuators

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Figure 3: Artist' view of the Terra spacecraft in orbit (image credit: NASA)

The design life of the Terra spacecraft is six years. The spacecraft bus is of size of 6.8 m (length) x 3.5 m (diameter) and has a total launch mass of 5,190 kg. The total payload mass is 1155 kg.

RF communications: The primary Terra telemetry data transmissions are via TDRS (Tracking & Data Relay Satellite) system. A steerable HGA (High Gain Antenna) and associated electronics are mounted on a deployed boom extending from the zenith side of the spacecraft. This location maximizes the amount of time available for TDRS communications via this antenna without obstruction by other pads of the spacecraft. Emergency communication is done via the nadir or zenith omni antenna. Command and engineering telemetry data are transmitted in S-band. The science data recorded onboard are transmitted via Ku-band at 150 Mbit/s. The nominal mode of operation is to acquire two 12 minute TDRSS contacts per orbit. During each TDRSS contact, both S-band and Ku-band transmission is being used.

The average data rate of the payload is 18.545 Mbit/s (109 Mbit/s peak); onboard recorders for data collection of one orbit. Mission operations are performed at GSFC. 9)

Broadcast of data: Besides Ku-band and S-band communication, Terra is also capable of downlinking science data via X-band. The X-band communication can be operated in three different modes, Direct Broadcast (DB), Direct Downlink (DDL) and Direct Playback (DP). DB and DDL is used to directly transmit real-time MODIS and ASTER science data respectively to users.

The DAS (Direct Access System) provides a backup option for direct transmission in X-band. DAS supports transmission of data to ground stations of qualified EOS users around the world. These users fall into three categories:

- EOS team participants and interdisciplinary scientists

- International meteorological and environmental agencies

- International partners who require data from their EOS instruments

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Figure 4: The Terra spacecraft in the cleanroom of LMMS at Valley Forge (image credit: LMMS)


Launch: The launch of the Terra spacecraft took place on Dec. 18, 1999 from VAFB, CA, on an Atlas-Centaur IIAS rocket.

Orbit: Sun-synchronous circular orbit, altitude = 705 km, inclination = 98.5º, period = 99 minutes (16 orbits per day, 233 orbit repeat cycles). The descending nodal crossing is at 10:30 AM.

Orbit determination is performed by TONS (TDRS Onboard Navigation System) which estimates Terra's position and velocity, drag coefficient, and master oscillator frequency bias. TONS is updated by Doppler measurements at the spacecraft's receivers and provides the attitude control software with a desired pointing ephemeris. Ground-based orbital elements are uplinked daily for backup navigation.

As of March 1, 2001, the Landsat-7, EO-1, SAC-C and Terra satellites are flying the so-called “morning constellation” or “morning train” (a loose formation demonstration of a single virtual platform). There is 1 minute separation between Landsat-7 and EO-1, a 15 minute separation between EO-1 and SAC-C, and a 1 minute separation between SAC-C and Terra. The objective is to compare coincident observations (imagery) from various instruments (synergistic effects). 10)

Figure 5: NASA's Terra mission at 10 years on-orbit (video credit: NASA)




Mission status

• September 9, 2019: The Serengeti is the site of the largest unaltered animal migration in the world. Around 1.5 million wildebeest—translating to “wild cattle” in Afrikaans—travel around the Serengeti plains for about seven months every year in search of pasture and water. The migration is considered one of the natural wonders of the world, attracting hundreds of thousands of tourists each year. 11)

- The journey of the wildebeest begins at the southern tip of the Serengeti plains in a region of Tanzania called Ndutu. The area is known for its short grass, which is rich in nutrients. From December to March, the majority of wildebeest congregate in Ndutu for food. Each February, wildebeest mothers give birth to thousands of calves here within a four- to six-week period—around 8,000 calves per day.

- Ndutu lies in the northern section of the Ngorongoro Conservation Area. The Ngorongoro landscape originated some 20 million years ago when the eastern side of Africa started to crack and rift. The rifting allowed for Earth's crust to thin and for molten materials to pile up and form volcanoes. Today, the Ngorongoro area includes a volcanic caldera. The ash left behind by the ancient volcanoes makes the soil here fertile for crops (outside of the conservation area) and for the savanna grasslands that feed so many animals.

- The Serengeti ecosystem—determined by the area covered by the migration—extends from the Maswa Game Reserve (Tanzania) to the south, to the Grumeti and Ikorongo Game Reserves (Tanzania) in the east, to Maasai Mara National Reserve in the north in Kenya, and to Loliondo Game Controlled Area (Tanzania) in the west. The Serengeti National Park is located in the center and covers around 15,000 km2 (5,800 square miles).

- When the drought arrives around April and May, the wildebeest leave Ndutu to begin a clockwise migration around the plains following the rains and the lush grasses they help sprout. The patterns have been repeating for at least a million years, according to the fossil record.

- Around May, the wildebeest first head for the long grass plains and woodland of the Serengeti’s western corridor, near Lake Victoria. By June or July, they arrive in the northern Serengeti plains, where they encounter arguably the hardest parts of their journey: the crocodile-infested Grumeti and Mara Rivers. The Grumeti lies adjacent to the Serengeti National Park, whereas the Mara is the only river that flows perennially through the park. The Mara River is also the major obstacle separating the wildebeest from the short, sweet grasses in Maasai Mara in Kenya. Many tourists visit from July to October for the chance to see thousands of wildebeest cross the river.

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Figure 6: This image shows a clear view of the Serengeti plains on February 4, 2018, as observed by the MODIS instrument on the NASA’s Terra satellite (image credit: NASA Earth Observatory image by Lauren Dauphin, using MODIS data from NASA EOSDIS/LANCE and GIBS/Worldview, story by Kasha Patel)

- By November of each year, the rainy season begins again in the southern Serengeti and the wildebeest return to Ndutu. In total, the wildebeest—along with hundreds of thousands of zebras, gazelles, and predators who join the journey—travel about 1,000 km.

- Since the migration is triggered by the dry season and rains, the exact timing and locations of the migration can vary from year to year. In 2019, the wildebeest were spotted crossing the Mara River earlier than usual as the dry season arrived early. Research suggests that variations in seasonal flooding and drought (due to climate change) may further alter when and where the wildebeest migrate.

• August 27, 2019: Every summer, vast expanses of the Canadian prairie in Saskatchewan, Alberta, and Manitoba turn a bright shade of yellow. The reason: canola fields reaching peak bloom. 12)

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Figure 7: The MODIS instrument on on NASA’s Terra satellite captured this image of yellow-tinged fields stretching across the three provinces on July 22, 2019 (image credit: NASA Earth Observatory, image by Lauren Dauphin, using MODIS data from NASA EOSDIS/LANCE and GIBS/Worldview. Story by Adam Voiland)

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Figure 8: A day later, OLI (Operational Land Imager) on Landsat-8 acquired a more-detailed view of canola in bloom near Regina, Saskatchewan (image credit: NASA Earth Observatory, image by Lauren Dauphin, using Landsat data from the U.S. Geological Survey, Story by Adam Voiland)

- Canola, a cultivar of rapeseed, is a member of the Brassica family, which includes cabbages and mustards. After flowering, canola plants produce brown oil-rich seeds that are about the size of poppies. When ground up, these seeds yield an oil that is widely used for cooking and high-protein meal used in animal feed.

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Figure 9: OLI detail image of canola in bloom near Regina, Saskatchewan (image credit: NASA Earth Observatory, image by Lauren Dauphin, using Landsat data from the U.S. Geological Survey, Story by Adam Voiland)

- According to the Canada Canola Association, Canadian farmers began to grow rapeseed during World War II to produce an inedible oil that was used as a lubricant in steam engines. In the decades following the war, Canadian plant breeders developed new varieties of rapeseed that had much lower levels of glucosinolates and erucic acids—undesirable substances that made rapeseed products taste bad or were thought to cause health problems. In 1978, the Western Canadian Oilseed Crushers trademarked these “double low” rapeseeds as canola (shorthand for Canadian oil, low acid).

- In recent decades, canola has become a cash crop for Canada, with much of the harvest getting exported. Since the mid-1980s, the footprint has spread significantly, with the total canola-growing area increasing by more than threefold, with particularly fast growth in Saskatchewan. The biggest importer of canola oil and meal is the United States, accounting for about 52 percent of oil exports and 69 percent of meal exports in 2018, according to the Canadian Canola Association.

• July 10, 2019: Scientists using NASA satellite observations have discovered the largest bloom of macroalgae in the world. In a paper published on July 5, 2019, in Science, researchers described new observations of the “Great Atlantic Sargassum Belt.” 13) 14)

- Led by researchers from the University of South Florida (USF) College of Marine Science, the team confirmed that the belt of brown macroalgae called Sargassum can grow so large that it blankets the surface of the tropical Atlantic Ocean from the west coast of Africa to the Gulf of Mexico. This happened in 2018 when more than 20 million tons of Sargassum—heavier than 200 fully loaded aircraft carriers—floated in surface waters and wreaked havoc on shorelines in the tropical Atlantic, the Caribbean Sea, and the Gulf of Mexico.

- The scientists used environmental data and some direct ocean sampling to suggest that the belt forms seasonally in response to two key nutrient inputs. In the spring and summer, Amazon River discharge adds nutrients to the ocean, and those nutrients may have increased in recent years due to increased deforestation and fertilizer use. In the winter, upwelling off the West African coast delivers nutrients from deep waters to the ocean surface where the Sargassum grows. Based on numerical simulations, the scientists found that the bloom takes its shape in response to prevailing ocean currents.

- “The evidence for nutrient enrichment is preliminary and based on limited field data and other environmental data, and we need more research to confirm this hypothesis,” said USF scientist Chuanmin Hu, who led the study and has studied Sargassum using satellites since 2006. “On the other hand, based on the last 20 years of data, I can say that the belt is very likely to be a new normal.”

- Hu spearheaded the work with first author Mengqiu Wang, a postdoctoral scholar in his Optical Oceanography Lab at USF. The team included others from USF, Florida Atlantic University, and Georgia Institute of Technology. Key data for the study came from the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on NASA’s Terra and Aqua satellites.

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Figure 10: This map depicts the monthly mean density of Sargassum in the Atlantic Ocean in each July from 2011 to 2018 (image credit: NASA Earth Observatory images by Joshua Stevens, using MODIS data courtesy of Wang, M., et al. (2019). Story by Kristen Kusek, University of South Florida; edited by Michael Carlowicz. This research was funded by NASA’s Earth Science Division, the NOAA RESTORE Science Program, the JPSS/NOAA Cal/Val project, the National Science Foundation, and a William and Elsie Knight Endowed Fellowship)

- In patchy doses in the open ocean, Sargassum contributes to ocean health by providing habitat for turtles, crabs, fish, and birds and by producing oxygen via photosynthesis. But too much of this seaweed makes it hard for certain marine species to move and breathe, especially when the mats crowd the coast. When Sargassum dies and sinks to the ocean bottom in large quantities, it can smother corals and seagrasses. On the beach, rotten Sargassum releases hydrogen sulfide gas and smells like rotten eggs.

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Figure 11: This photo shows abundant Sargassum off of the Florida Keys in 2014 (image credit: NASA Earth Observatory)

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Figure 12: The photo shows Sargassum along a beach in Cancun, Mexico in 2015 (image credit: NASA Earth Observatory)

- Before 2011, most of the pelagic Sargassum in the ocean was primarily found floating in patches around the Gulf of Mexico and Sargasso Sea. The Sargasso Sea is located on the western edge of the central Atlantic Ocean and named after its popular algal resident. Christopher Columbus first reported Sargassum in the 15th century, and many boaters are familiar with this seaweed.

- In 2011, Sargassum populations started to explode in places they hadn’t been before, and it arrived in vast amounts that suffocated shorelines and introduced a nuisance for local environments and economies. Some countries, such as Barbados, declared a national emergency in 2018 because of the toll this once-healthy seaweed took on tourism.

- “The ocean’s chemistry must have changed in order for the blooms to get so out of hand,” Hu said. Sargassum reproduces vegetatively, and it probably has several initiation zones around the Atlantic Ocean. It grows faster when nutrient conditions are favorable and when its internal clock ticks in favor of reproduction.

- Wang, Hu, and colleagues analyzed fertilizer consumption patterns in Brazil, Amazon deforestation rates, Amazon River discharge, and nitrogen and phosphorus measurements taken from parts of the Atlantic Ocean, among other ocean properties. While the data are preliminary, the pattern seems clear: the explosion in Sargassum correlates to increases in deforestation and fertilizer use, both of which have increased since 2010.

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Figure 13: This plot shows the monthly mean area covered by the seaweed, as observed by MODIS from 2000 to 2018 (image credit: NASA Earth Observatory)

- The team identified key factors critical to bloom formation: a large seed population in the winter left over from a previous bloom; nutrient input from West Africa upwelling in winter; and nutrient input in the spring or summer from the Amazon River. In addition, Sargassum only grows well when salinity is normal and surface temperatures are normal or cooler. As noted in the images above, major blooms occurred in every year between 2011 and 2018 except 2013. No bloom occurred that year because the seed populations measured during winter of 2012 were unusually low, Wang said.

- “This is all ultimately related to climate change because it affects precipitation and ocean circulation and even human activities, but what we’ve shown is that these blooms do not occur because of increased water temperature,” Hu said. “They are probably here to stay.”

- “The scale of these blooms is truly enormous, making global satellite imagery a good tool for detecting and tracking their dynamics through time,” said Woody Turner, manager of NASA’s Ecological Forecasting Program.

• June 25, 2019: Unlike some of its perpetually active neighbors on the Kamchatka Peninsula, Raikoke Volcano on the Kuril Islands rarely erupts. The small, oval-shaped island most recently exploded in 1924 and in 1778. 15)

- The dormant period ended around 4:00 a.m. local time on June 22, 2019, when a vast plume of ash and volcanic gases shot up from its 700-meter-wide crater. Several satellites—as well as astronauts on the International Space Station—observed as a thick plume rose and then streamed east as it was pulled into the circulation of a storm in the North Pacific.

- On the morning of June 22, astronauts shot a photograph (Figure 14) of the volcanic plume rising in a narrow column and then spreading out in a part of the plume known as the umbrella region. That is the area where the density of the plume and the surrounding air equalize and the plume stops rising. The ring of clouds at the base of the column appears to be water vapor.

- “What a spectacular image. It reminds me of the classic Sarychev Peak astronaut photograph of an eruption in the Kuriles from about ten years ago,” said Simon Carn, a volcanologist at Michigan Tech. “The ring of white puffy clouds at the base of the column might be a sign of ambient air being drawn into the column and the condensation of water vapor. Or it could be a rising plume from interaction between magma and seawater because Raikoke is a small island and flows likely entered the water.”

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Figure 14: Astronaut photograph ISS059-E-119250 was acquired on June 22, 2019, with a Nikon D5 digital camera and is provided by the ISS Crew Earth Observations Facility and the Earth Science and Remote Sensing Unit, Johnson Space Center. The image was taken by a member of the Expedition 59 crew (image credit: NASA Earth Observatory, story by Adam Voiland)

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Figure 15: The MODIS instrument on NASA’s Terra satellite acquired this image on the morning of 22 June. At the time, the most concentrated ash was on the western edge of the plume, above Raikoke. By the next day, just a faint remnant of the ash remained visible to MODIS [image credit: NASA Earth Observatory, image by Joshua Stevens using MODIS data from NASA EOSDIS/LANCE and GIBS/Worldview, Story by Adam Voiland, with information from Erik Klemetti (Denison University), Simon Carn (Michigan Tech), and Andrew Prata (Barcelona Supercomputing Center)]

- The image of Figure 16 of VIIRS on Suomi NPP shows the plume a few hours later. After an initial surge of activity that included several distinct explosive pulses, activity subsided and strong winds spread the ash across the Pacific.

- Since ash contains sharp fragments of rock and volcanic glass, it poses a serious hazard to aircraft. The Tokyo and Anchorage Volcanic Ash Advisory Centers have been tracking the plume closely and have issued several notes to aviators indicating that ash had reached an altitude of 13 kilometers. Meanwhile, data from the CALIPSO satellite indicate that parts of the plume may have reached 17 kilometers.

- In addition to tracking ash, satellite sensors can also track the movements of volcanic gases. In this case, Raikoke produced a concentrated plume of sulfur dioxide (SO2) that separated from the ash and swirled throughout the North Pacific as the plume interacted with the storm.

- “Radiosonde data from the region indicate a tropopause altitude of about 11 km, so altitudes of 13 to 17 km suggest that the eruption cloud is mostly in the stratosphere,” said Carn. “The persistence of large SO2 amounts over the last two days also indicates stratospheric injection.”

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Figure 16: This image is an oblique composite view based on data from VIIRS (Visible Infrared Imaging Radiometer Suite) on Suomi NPP (image credit: NASA Earth Observatory, image by Joshua Stevens, using VIIRS data of the Suomi National Polar-orbiting Partnership)

• June 11, 2019: Los Glaciares National Park in Patagonia gets its name from the plentiful glaciers flowing from the flanks of the Andes Mountains. Where some of the park’s most notable glaciers end, a series of colorful glacial lakes begin. 16)

- Most of these glaciers end in water, where their fronts can lose ice by melting and through calving icebergs. Numerous studies have focused on the glaciers on the west side of the southern icefield that dispense ice and meltwater to the Pacific Ocean. But the icefield is losing plenty of ice on its eastern side too, through glaciers that end in freshwater lakes.

- Lago Argentino and Lago Viedma are the two main freshwater lakes connected to Los Glaciares National Park (Figure 17). These lakes, as well as nearby Lago San Martin, are filled with so much fine sediment from the glaciers—also known as glacial flour—that they appear milky turquoise when viewed from space.

- Notice that Lago Viedma is much grayer than Lago Argentino and Lago San Martin. That’s because Lago Viedma receives sediment-rich-water directly from Viedma glacier—the second-largest in Patagonia. The meltwater pouring out near Upsala glacier is equally gray, but the color changes as the water flows through the fjord. Most of the sediment particles settle to the bottom before reaching the main body of Lago Argentina, which appears bluer.

- In recent years, scientists have identified ways in which these freshwater-calving glaciers differ from those that end in seawater. Teasing out those differences is important for understanding the various mechanisms responsible for melting and calving.

- Shin Sugiyama, a researcher at Hokkaido University, showed that the high sediment concentration in the freshwater lakes can affect the water’s thermal structure near the ice front. The sediment causes cold, turbid meltwater from the bottom of a submerged glacier to stay at depth. In contrast, cold meltwater from the bottom of a glacier submerged in seawater tends to rise and be replaced with warm water. That means that melting at a glacier’s front in a freshwater lake is probably limited compared to that of its western, seawater-terminating counterpart—at least at depth.

- Sugiyama pointed out that even among the freshwater lakes there could be differences in the ice-water interaction. “As suggested by the water colors, conditions are very different at each lake,” Sugiyama said. “I am curious how those glaciers ending in different lakes behave differently in the future.”

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Figure 17: MODIS on NASA's Terra satellite acquired this natural-color image of the South Patagonian Icefield on February 4, 2019. Spanning about 13,000 km2 of Chile and Argentina, the icefield is the southern hemisphere’s largest expanse of ice outside of Antarctica. Together with the northern icefield, ice in this region is being lost at some of the highest rates on the planet. Much of the loss happens through more than 60 major outlet glaciers—channels of ice that descend from the icefield (image credit: NASA Earth Observatory, image by Lauren Dauphin, using MODIS data from NASA EOSDIS/LANCE and GIBS/Worldview. Story by Kathryn Hansen)

• June 6, 2019: As summer approaches and hours of sunlight increase in the northern hemisphere, the oceans come alive with blooms of phytoplankton. In early June 2019, a stunning bloom colored the waters off the coast of Norway. 17)

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Figure 18: Phytoplankton in the Norwegian Sea are visible in this image, acquired on June 5, 2019, with the MODIS instrument on NASA’s Terra satellite. The bloom, shown here off Nordland and Trøndelag counties, likely includes plenty of Emiliania huxleyi—a species of coccolithophore with white scale-like shells made of calcium carbonate. The mixture of calcium carbonate and ocean water appears milky blue-green. Some of the color may come from sediment or from other species of phytoplankton (image credit: NASA Earth Observatory image by Joshua Stevens, using MODIS data from NASA EOSDIS/LANCE and GIBS/Worldview, Story by Kathryn Hansen)

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Figure 19: This image, photographed by Stig Bjarte Haugen of the Norwegian Institute of Marine Research, shows what E. huxleyi looks like though a microscope. (Note that the green hue was added for aesthetic reasons.) Each microalga is just a fraction of the diameter of a human hair. But when rapid cell division leads to an explosive bloom, you get a high enough concentration that they become visible from space (image credit: NASA Earth Observatory, photo by Stig Bjarte Haugen/Norwegian Institute of Marine Research)

- Previous natural-color satellite images show signs of the milky blue-green color in this area starting in mid-May. Follow the coastline south, and you can see more colorful phytoplankton visible between areas of cloud cover. Even the waters of some fjords, including Sognefjord (Norway’s largest and deepest)—are abloom with E. huxleyi.

- E. huxleyi is harmless to fish and people. The same is not true, however, for the species Chrysochromulina leadbeateri. Although not visible in this image, high concentrations of Chrysochromulina were responsible for suffocating millions of farmed salmon in northern Norway. According to news reports, this type of phytoplankton is commonly found in the waters around Norway, but warm weather contributed to their rapid spread in May.

• June 4, 2019: Situated along the Nile River, the modern city of Luxor stands as a relic of one of the most venerated metropolises of ancient Egypt. Then known as Thebes, the city was the capital of ancient Egypt at two separate times and home to prominent temples, chapels, and towers. Although those structures have weathered over the centuries, the ruins still make Luxor one of the world’s greatest open air museums. 18)

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Figure 20: This image of Luxor and its surroundings was acquired on 15 November 2018, by the ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) instrument on NASA’s Terra satellite. This false-color scene is shown in green, red, and near-infrared light, a combination that helps differentiate components of the landscape. Water is black, vegetation is red, and urban areas are brown to gray (image credit: NASA Earth Observatory, image by Lauren Dauphin, using data from NASA/METI/AIST/Japan Space Systems, and U.S./Japan ASTER Science Team. Story by Kasha Patel)

- The legendary temples of Luxor attract tourists from around the world. The Luxor Temple (now with a fast-food restaurant next door—not a relic of ancient Egypt) lies at the modern city’s center. The temple served as “the place of the First Occasion” where the god Amun-Ra (to whom the city of Thebes was dedicated) experienced rebirth during the pharaoh’s annual coronation ceremony. Over time, the sandstone temple has eroded from contact with salty groundwater, so it is currently undergoing treatment.

- Another notable landmark is the Karnak Temple Complex, a collection of temples that were developed over more than 1,000 years. At its peak, Karnak was one of the largest religious complexes in the world, covering 80 hectares (200 acres). It is home to one of the most significant and largest religious building ever built—the Temple of Amun-Ra, where the god was believed to have lived on Earth with his wife and son (who also have temples in the complex). A row of human-headed sphinxes—known as the Avenue of Sphinxes—once lined the three-kilometer path from Karnak to the Luxor Temple.

- The Egyptians also created massive underground mausoleums to bury and honor their pharaohs in the area. On the west bank of the Nile River, near the hills, Egyptians built an inconspicuous vault called the “Valley of Kings,” where more than 60 tombs have been found. One of the most famous housed the boy King Tutankhamun (commonly known as King Tut). That tomb was found almost entirely preserved—the most intact tomb ever found.

• May 22, 2019: When satellites observe large dust plumes over Japan, the dust typically comes from vast deserts in Central Asia and arrives on westerly winds. However, on May 20, 2019, the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra satellite acquired an image of a different type of dust event—a plume streaming from farmland near Shira and Kiyosato in northern Hokkaido. 19)

- The seasonal rhythms of farming likely contributed as well. Landsat satellite imagery suggests that many fields in the area had little green vegetation or may have been tilled recently, both of which would make it easier for gusty winds to pick up dust.

- Scientists who routinely monitor global dust storm activity say it is unusual for Japan to produce such a large dust plume. Though on average there are 20 teragrams (20 x 1012 grams, or 20 million tons) of dust in the air at any one time, most of it comes from large deserts in North Africa, the Middle East, and Central Asia. Only about 5 percent of global emissions come from middle and high-latitude areas.

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Figure 21: Unusually dry weather in April and May 2019 likely dried out the land surface and made it easier for strong southerly winds to lift so much dust. In the nearby town of Betsukai, the Japan Meteorological Agency recorded wind gusts as fast as 60 km/hr on May 20, noted Teppei Yasunari, an atmospheric scientist with Hokkaido University’s Arctic Research Center. Dust storms typically can occur if winds exceed 40 km/hr (image credit: NASA Earth Observatory, image by Adam Voiland, using MODIS data from NASA EOSDIS/LANCE and GIBS/Worldview. Caption by Adam Voiland)

• May 6, 2019: As soon as the snow melts in springtime, widespread fires typically emerge in far northeastern Russia. On 3 May 2019, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired this false-color image of a large burn scar along the Amur River in Russia’s Khabarovsk region. The image was composed using visible and infrared light (bands 7-2-1), which makes it easier to distinguish burned areas. 20)

- The Amur River Valley is a mosaic of farmland, forests, shrubs, and grasslands. It is known for being a productive agricultural region, and most of these fires were probably triggered by farmers burning off old plant debris to prepare their fields for a new crop. Some of the fires may have begun on farmland, but then escaped control and grew larger as they moved into nearby wildlands.

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Figure 22: The large burn scar near the center of the image emerged west of the town of Naykhin on April 28, 2019, and then spread rapidly north through swampy grasslands near Lake Bolon. Separate fires that burned within the past few weeks left the scars to the north, west, and south (image credit: NASA Earth Observatory image by Lauren Dauphin, using MODIS data from NASA EOSDIS/LANCE and GIBS/Worldview and using Landsat data from the U.S. Geological Survey. Story by Adam Voiland)

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Figure 23: The fire near Naykhin on 30 April 2019 caught the attention of atmospheric scientists for producing what was likely the first pyrocumulus of the year in the Northern Hemisphere. Pyrocumulus clouds—sometimes called “fire clouds”—are tall, cauliflower-shaped, and appear as opaque white patches bubbling up from darker smoke in satellite images. Fires that produce pyrocumulus clouds tend to spread smoke much higher and farther than those that do not (image credit: NASA Earth Observatory image by Lauren Dauphin, using MODIS data from NASA EOSDIS/LANCE and GIBS/Worldview and using Landsat data from the U.S. Geological Survey. Story by Adam Voiland)

- In order for scientists to classify a cloud as pyrocumulus, cloud top temperatures observed by satellites must be -40°C (-40°F) or cooler. According to University of Wisconsin meteorologist Scott Bachmeier, this cloud passed that threshold at 03:10 Universal Time, a few hours after the Operational Land Imager (OLI) on Landsat 8 acquired the natural-color shown image above. At that time, low-lying gray smoke streamed from an actively burning fire front as the beginning stages of the pyrocumulus cloud billowed up over the fire.

• May 02, 2019: With some areas that receive just a few millimeters of rain per year and some that see none at all, the Atacama Desert in northern Chile is one of the driest places in the world. When it does rain, the landscape can transform. 21)

- The desert extends along the western edge of the Andes Mountains, which produce an intense rain shadow effect. The desert also sits next to a cool ocean current that chills the air and limits how much moisture it can hold. And often a zone of persistent high pressure blocks storms from moving into the area.

- Still, water occasionally finds its way to the Atacama, as it did in January and February 2019. Storms, which are usually restricted to the highest parts of the Andes, dropped enough rain in the foothills to cause damaging floods in Arica, Tarapacá, and Antofagasta. The western slopes of the Andes were hit particularly hard, with several ground-based weather stations recording between 100 – 200 millimeters (4 – 8 inches) of rain. Between February 4 – 6, 2019, satellites measured more than 50 millimeters falling in wide bands near Calama and Camiña. According to news reports, several people died, hundreds of homes were destroyed, and thousands of people lost power due to the floods.

- However, the rush of water left its mark on this hyper-arid region in a positive way, too. By March 2019, land surfaces that are typically brown and barren were blanketed with wildflowers and other vegetation. While the wildflowers are not easily visible in natural-color imagery from satellites, several sensors make observations of infrared light that make the greenup more apparent.

- The map depicts the Normalized Difference Vegetation Index (NDVI), a measure of the health and greenness of vegetation based on how much red and near-infrared light it reflects. Healthy vegetation with lots of chlorophyll reflects more near-infrared light and less visible light.

- Wildflower blooms happen occasionally in the southern part of the Atacama Desert in winter. The last big event was in 2017. “This year is different and less studied because it is occurring in austral fall and farther north,” said René Garreaud, an Earth scientist at the Universidad de Chile. “It should be interesting to investigate the cause of last summer’s storms and see if the rain increases groundwater levels in the Pampa del Tamarugal.

- A recent analysis of satellite NDVI observations collected between 1981 and 2015 identified 13 Atacama greening events, with most beginning in the winter and remaining until the following summer.

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Figure 24: The NDVI anomaly map is based on data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite between April 14 – 28, 2019. The map contrasts vegetation health against the long-term average (2000 – 2012) for that period. Greens indicate vegetation that is more widespread or abundant than normal for the time of year. The most greening occurred at elevations between 2500 – 3000 meters in a band that extended for hundreds of kilometers [image credit: NASA Earth Observatory, image by Lauren Dauphin, using MODIS data from NASA EOSDIS/LANCE and GIBS/Worldview. Story by Adam Voiland, with information from René Garreaud (Universidad de Chile)]

• April 22, 2019: Once the second-largest saltwater lake in the Middle East, Lake Urmia attracted birds and bathers to bask in its turquoise waters in northwest Iran. Then beginning in the 1970s, nearly three decades of drought and high water demands on the lake shriveled the basin, shrinking it by 80 percent. 22)

- Recent torrential rains have replenished the water levels of this aquatic gem once known as “the turquoise solitaire of Azerbaijan.” At its greatest extent, Lake Urmia once covered a surface area of 5,000 km2 (2,000 square miles).

- The fresh pulse of water came from intense rains during the fall of 2018 and spring 2019. In late March and early April 2019, 26 of Iran’s 31 provinces were affected by deadly flooding from the rain and the seasonal melting of snow cover in the mountains.

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Figure 25: These images, acquired by Terra MODIS, show Lake Urmia (also Orumiyeh or Orumieh) on 5 February, 2019, and 12 April 12 2019, before and after the recent floods in the region. The rains were reported to be the heaviest Iran has seen in 50 years. After the spring rains, the depth of the lake increased by 62 cm (24 inches) compared to the spring of 2018 (image credit: NASA Earth Observatory, images by Lauren Dauphin, using MODIS data from NASA EOSDIS/LANCE and GIBS/Worldview. Story by Kasha Patel)

• April 9, 2019: Most people will never see Pine Island Glacier in person. Located near the base of the Antarctic Peninsula—the “thumb” of the continent—the glacier lies more than 2,600 km (1,600 miles) from the tip of South America. That’s shorter than a cross-country flight from New York to Los Angeles, but there are no runways on the glacier and no infrastructure. Only a handful of scientists have ever set foot on its ice. 23)

- While this outlet glacier is just one of many around the perimeter of Antarctica, data collected from the ground, air, and space confirm that Pine Island is worth extra attention. It is, along with neighboring Thwaites Glacier, one of the main pathways for ice entering the Amundsen Sea from the West Antarctic Ice Sheet and one the fastest-retreating glaciers in Antarctica. Collectively, the region contains enough vulnerable ice to raise global sea level by 1.2 meters (4 feet).

Figure 26: The animation shows a wide view of Pine Island Glacier (PIG) and the long-term retreat of its ice front. Images were acquired by the MODIS instrument on NASA’s Terra satellite from 2000 to 2019. Notice that there are times when the front appears to stay in the same place or even advance, though the overall trend is toward retreat (image credit: NASA Earth Observatory animation by Lauren Dauphin, using MODIS data from NASA EOSDIS/LANCE and GIBS/Worldview)

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Figure 27: NASA Earth Observatory map by Lauren Dauphin, using Reference Elevation Model of Antarctica (REMA) data from the Polar Geospatial Center at the University of Minnesota.

- “The process of how a large outlet glacier like Pine Island ‘shrinks’ has some interesting twists,” said Bob Bindschadler, an emeritus NASA glaciologist who landed on Pine Island Glacier’s ice shelf in 2008.

- Decades of investigations have given scientists a better idea of the quirks of PIG’s behavior. For example, data collected during science flights in 2009 led researchers to discover a deep-water channel (Figure 28) that could funnel warm water to the glacier’s underbelly and melt it from below.

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Figure 28: NASA Earth Observatory map by Jesse Allen, based on a model by Michael Studinger of NASA IceBridge and gravity data from Columbia University

- Bindschadler explained that a shrinking outlet glacier is usually doing three things: thinning (mostly at the seaward edge), retreating, and accelerating. The acceleration stretches the glacier, causing the thinning and likely making the ice more prone to crevassing (cracking) “upstream.”

- Fractures near the seaward edge cause the ice to calve off as icebergs, a normal part of life for glaciers that extend over water. If icebergs calve off at a rate that matches the glacier’s acceleration, the ice front stays in the same place.

- But over the long term at Pine Island, you can see that the ice front has retreated inland, which means the calving rate has increased more than the glacier has accelerated. “This underlies our concern that retreating outlet glaciers can ‘shrink’ rapidly,” Bindschadler said.

• March 22, 2019: On Dec. 18, 2018, a large "fireball" - the term used for exceptionally bright meteors that are visible over a wide area - exploded about 16 miles (26 km) above the Bering Sea. The explosion unleashed an estimated 173 kilotons of energy, or more than 10 times the energy of the atomic bomb blast over Hiroshima during World War II. 24)

- Two NASA instruments aboard the Terra satellite captured images of the remnants of the large meteor. The image sequence shows views from five of nine cameras on the Multi-angle Imaging SpectroRadiometer (MISR) instrument taken at 23:55 UTC (Coordinated Universal Time), a few minutes after the event. The shadow of the meteor's trail through Earth's atmosphere, cast on the cloud tops and elongated by the low sun angle, is to the northwest. The orange-tinted cloud that the fireball left behind by super-heating the air it passed through can be seen below and to the right the center of Figure 29.

Figure 29: This image sequence shows views from five of nine cameras on the MISR instrument, taken at 23:55 UTC (image credit: NASA/GSFC/LaRC/JPL-Caltech, MISR Team)

- The fireball observed on 18 December 2018 was the most powerful meteor to be observed since 2013; however, given its altitude and the remote area over which it occurred, the object posed no threat to anyone on the ground. Fireball events are actually fairly common and are recorded in the NASA Center for Near Earth Object Studies database.

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Figure 30: The MODIS instrument captured this true-color image showing the remnants of a meteor's passage, seen as a dark shadow cast on thick, white clouds on Dec. 18, 2018. MODIS captured the image at 23:50 UTC (image credit: NASA/GSFC)

• March 12, 2019: Tropical Cyclone Idai is poised to move inland over East African countries that were already soaked by flooding rain from the same storm system earlier this month. 25)

- The storm system first developed as a tropical disturbance on March 3 and grew by March 5 into a tropical depression with winds measuring 30 knots. In the process, it dropped heavy rain on Mozambique and Malawi and spawned deadly floods. By March 11, the storm had tracked eastward into the warm channel between the coast of Africa and Madagascar, where it strengthened into an intense tropical cyclone.

- Now on a southwestward track, forecasts call for Idai to reach Mozambique by March 14-15, bringing a second round of wind and heavy rain to the region.

- “Several cyclones in the past have started over Mozambique and then moved over water and intensified into more organized systems, although this type of situation is not common,” said Corene Matayas, a researcher at University of Florida who has studied cyclones in this area. It is relatively common, however, to see cyclone tracks in the Mozambique Channel that meander and loop, due to weak steering currents.

- Cyclones that form in the channel tend to be weaker than those that form over the Southwest Indian Ocean, north and east of Madagascar. But Matayas points out that regardless of where a cyclone forms, some have reached their highest intensity within a day before landfall. Tropical Cyclone Eline in February 2000, for example, passed over Madagascar and the Mozambique Channel, and then quickly intensified just before landfall in Mozambique.

- “Keys to intensification are warm ocean waters to sufficient depth, the absence of strong winds in the upper troposphere, and being contained inside of a moist air mass,” Matayas said. “These conditions are all present right now.”

- Most tropical cyclone activity in the Southwest Indian basin occurs between October and May, with activity peaking in mid-January and again in mid-February to early March. Idai is the seventh intense tropical cyclone of the basin’s 2018-2019 season.

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Figure 31: MODIS on on NASA’s Terra satellite acquired this image of the cyclone on March 12, 2019, as it spun across the Mozambique Channel. Around this time, the potent storm carried maximum sustained winds of about 90 knots (105 miles/165 kilometers per hour)—equivalent to a category 2 storm on the Saffir-Simpson wind scale (image credit: NASA Earth Observatory, image by Lauren Dauphin, using MODIS data from NASA EOSDIS/LANCE and GIBS/Worldview. Story by Kathryn Hansen)

• March 4, 2019: Unseasonably warm temperatures swept across the United Kingdom and much of Europe in February 2019. The month started with snow and freezing temperatures in the United Kingdom, but provisional statistics from the UK Met Office indicate February 2019 was the second warmest February on record for the country. England, Scotland, and Wales all recorded their warmest meteorological winter days and hottest February days since record-keeping began in 1910. 26)

- Kew Gardens in London recorded 21.2° Celsius (70.1° Fahrenheit) on February 26, a new record for the warmest winter day in the United Kingdom. Scotland experienced its warmest winter day with 18.3°C (64.9°F) at Aboyne, Aberdeenshire, on February 21. Wales also broke its existing record, reaching 20.8°C (69.4°C) in Porthmadog, Gywnedd, on February 26.

- The high temperatures were the product of a large area of high pressure that stalled and trapped warm air over Europe. The clear, dry conditions allowed more sunshine to warm the ground. (February 2019 was the second sunniest on record for the United Kingdom as a whole.) The high-pressure system also drew in warm air from the North Atlantic near the Canary Islands.

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Figure 32: The maps of Figures 32 and 33 show land surface temperature anomalies for February 11-25, 2019. Reds and oranges depict areas that were hotter than average for the same two-week period from 2000-2012; blues were colder than average. White pixels were normal, and gray pixels did not have enough data, most likely due to excessive cloud cover. This temperature anomaly map is based on data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite (image credit: NASA Earth Observatory, image by Joshua Stevens, using data from the Level 1 and Atmospheres Active Distribution System (LAADS) and Land Atmosphere Near real-time Capability for EOS (LANCE), story by Kasha Patel)

Legend to Figure 32: The map depicts land surface temperatures (LSTs), not air temperatures. LSTs reflect how hot the surface of the Earth would feel to the touch and can sometimes be significantly hotter or cooler than air temperatures.

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Figure 33: While the UK was experiencing record-breaking warmth, increased temperatures spread across central and eastern Europe—so much that spring barley harvesting may start early. Forecasters say the weather over central Europe will be warmer and drier-than-normal through May (image credit: NASA Earth Observatory, image by Joshua Stevens, using data from the Level 1 and Atmospheres Active Distribution System (LAADS) and Land Atmosphere Near real-time Capability for EOS (LANCE), story by Kasha Patel)

• February 28, 2019: The 2015-2016 El Niño event brought weather conditions that triggered regional disease outbreaks throughout the world, according to a new NASA study that is the first to comprehensively assess the public health impacts of the major climate event on a global scale. 27)

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Figure 34: Increased sea surface temperatures in the equatorial Pacific Ocean characterizes an El Niño, which is followed by weather changes throughout the world (image credit: NASA Goddard’s Scientific Visualization Studio)

- El Niño is an irregularly recurring climate pattern characterized by warmer than usual ocean temperatures in the equatorial Pacific, which creates a ripple effect of anticipated weather changes in far-spread regions of Earth. During the 2015-2016 event, changes in precipitation, land surface temperatures and vegetation created and facilitated conditions for transmission of diseases, resulting in an uptick in reported cases for plague and hantavirus in Colorado and New Mexico, cholera in Tanzania, and dengue fever in Brazil and Southeast Asia, among others.

- “The strength of this El Niño was among the top three of the last 50 years, and so the impact on weather and therefore diseases in these regions was especially pronounced,” said lead author Assaf Anyamba, a research scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “By analyzing satellite data and modeling to track those climate anomalies, along with public health records, we were able to quantify that relationship.”

- The study utilized a number of climate datasets, among them land surface temperature and vegetation data from the Moderate Resolution Imaging Spectroradiometer aboard NASA’s Terra satellite, and NASA and National Oceanic and Atmospheric Administration precipitation datasets. The study was published on 13 February 2019 in the journal Nature Scientific Reports. 28)

- Based on monthly outbreak data from 2002 to 2016 in Colorado and New Mexico, reported cases of plague were at their highest in 2015, while the number of hantavirus cases reached their peak in 2016. The cause of the uptick in both potentially fatal diseases was an El Niño-driven increase in rainfall and milder temperatures over the American Southwest, which spurred vegetative growth, providing more food for rodents that carry hantavirus. A resulting rodent population explosion put them in more frequent contact with humans, who contract the potentially fatal disease mostly through fecal or urine contamination. As their rodent hosts proliferated, so did plague-carrying fleas.

- A continent away, in East Africa’s Tanzania, the number of reported cases for cholera in 2015 and 2016 were the second and third highest, respectively, over an 18-year period from 2000 to 2017. Cholera is a potentially deadly bacterial infection of the small intestine that spreads through fecal contamination of food and water. Increased rainfall in East Africa during the El Niño allowed for sewage to contaminate local water sources, such as untreated drinking water. “Cholera doesn’t flush out of the system quickly,” Anyamba said, “so even though it was amplified in 2015-2016, it actually continued into 2017 and 2018. We’re talking about a long-tailed, lasting peak.”

- In Brazil and Southeast Asia, during the El Niño dengue fever proliferated. In Brazil the number of reported cases for the potentially deadly mosquito-borne disease in 2015 was the highest from 2000 to 2017. In Southeast Asia, namely Indonesia and Thailand, the number of reported cases, while relatively low for an El Niño year, was still higher than in neutral years. In both regions, the El Niño produced higher than normal land surface temperatures and therefore drier habitats, which drew mosquitoes into populated, urban areas containing the open water needed for laying eggs. As the air warmed, mosquitoes also grew hungrier and reached sexual maturity more quickly, resulting in an increase in mosquito bites.

Figure 35: How the 2015-2016 El Niño triggered outbreaks across the globe (video credit: NASA Goddard's Scientific Visualization Studio)

- The strong relationship between El Niño events and disease outbreaks underscores the importance of existing seasonal forecasts, said Anyamba, who has been involved with such work for the past 20 years through funding from the U.S. Department of Defense. Countries where these outbreaks occur, along with the United Nations’ World Health Organization and Food and Agriculture Organization, can utilize these early warning forecasts to take preventive measures to minimize the spread of disease. Based on the forecast, the U.S. Department of Defense does pre-deployment planning, and the U.S. Department of Agriculture (USDA) takes measures to ensure the safety of imported goods.

- “Knowledge of the linkages between El Niño events and these important human and animal diseases generated by this study is critical to disease control and prevention, which will also mitigate globalization,” said co-author Kenneth Linthicum, USDA center director at an entomology laboratory in Gainesville, Florida. He noted these data were used in 2016 to avert a Rift Valley fever outbreak in East Africa. “By vaccinating livestock, they likely prevented thousands of human cases and animal deaths.”

- “This is a remarkable tool to help people prepare for impending disease events and take steps to prevent them,” said co-author William Karesh, executive vice president for New York City-based public health and environmental nonprofit EcoHealth Alliance. “Vaccinations for humans and livestock, pest control programs, removing excess stagnant water — those are some actions that countries can take to minimize the impacts. But for many countries, in particular the agriculture sectors in Africa and Asia, these climate-weather forecasts are a new tool for them, so it may take time and dedicated resources for these kinds of practices to become more utilized.”

- According to Anyamba, the major benefit of these seasonal forecasts is time. “A lot of diseases, particularly mosquito-borne epidemics, have a lag time of two to three months following these weather changes,” he said. “So seasonal forecasting is actually very good, and the fact that they are updated every month means we can track conditions in different locations and prepare accordingly. It has the power to save lives.”

• February 18, 2019: In Spanish, Sierra Nevada means “snowy mountain range.” During the past few months, the range has certainly lived up to its name. After a dry spell in December, a succession of storms in January and February 2019 blanketed the range. 29)

- In many areas, snow reports have been coming in feet not inches. Back-to-back storms in February dropped eleven feet (3 meters) of snow on Mammoth Mountain—enough to make it the snowiest ski resort in the United States. More than 37 feet (11 meters) have fallen at the resort since the beginning of winter, and meteorologists are forecasting that yet another storm will bring snow this week.

- Statistics complied by the California Department of Water Resources indicate that the mountain range had a snow water equivalent that was 130 percent of normal as of February 11, 2019. It was just 44 percent of normal on Thanksgiving 2018. Last season, on February 15, 2018, snow cover was at a mere 21 percent of normal.

- Some of the snow has come courtesy of atmospheric rivers, a type of storm system known for transporting narrow, low-level plumes of moisture across long ocean distances and dumping tremendous amounts of precipitation on land.

- The condition of Sierra Nevada snowpack has consequences that go well beyond ski season. Spring and summer melt from the Sierra Nevada plays a crucial role in recharging California’s reservoirs. Though conditions could change, California drought watchers are cautiously optimistic that the boost to the snowpack will insulate the state from drought this summer.

- The reservoirs are already in pretty good shape. Cal Water data show that most of the reservoirs are already more than half-full, and several have water levels that are above the historical average for the middle of February.

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Figure 36: A succession of storms in January and February dumped huge amounts of snow on the Sierra Nevada. The MODIS instrument on NASA's Terra satellite acquired these natural-color images of the Sierra Nevada on February 11, 2019, and February 15, 2018. In addition to the much more extensive snow cover in 2019, notice the greener landscape on the western slopes of the range (image credit: NASA Earth Observatory, images by Joshua Stevens, using MODIS data from NASA EOSDIS/LANCE and GIBS/Worldview. Story by Adam Voiland)

• February 12, 2019: The world is literally a greener place than it was twenty years ago, and data from NASA satellites has revealed a counterintuitive source for much of this new foliage. A new study shows that China and India—the world’s most populous countries—are leading the increase in greening on land. The effect comes mostly from ambitious tree-planting programs in China and intensive agriculture in both countries. 30)

- Ranga Myneni of Boston University and colleagues first detected the greening phenomenon in satellite data from the mid-1990s, but they did not know whether human activity was a chief cause. They then set out to track the total amount of Earth’s land area covered by vegetation and how it changed over time.

- The research team found that global green leaf area has increased by 5 percent since the early 2000s, an area equivalent to all of the Amazon rainforests. At least 25 percent of that gain came in China. Overall, one-third of Earth’s vegetated lands are greening, while 5 percent are growing browner. The study was published on February 11, 2019, in the journal Nature Sustainability. 31)

- “China and India account for one-third of the greening, but contain only 9 percent of the planet’s land area covered in vegetation,” said lead author Chi Chen of Boston University. “That is a surprising finding, considering the general notion of land degradation in populous countries from overexploitation.”

- This study was made possible thanks to a two-decade-long data record from the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on NASA’s Terra and Aqua satellites. An advantage of MODIS is the intensive coverage they provide in space and time: the sensors have captured up to four shots of nearly every place on Earth, every day, for the past 20 years.

- “This long-term data lets us dig deeper,” said Rama Nemani, a research scientist at NASA’s Ames Research Center and a co-author of the study. “When the greening of the Earth was first observed, we thought it was due to a warmer, wetter climate and fertilization from the added carbon dioxide in the atmosphere. Now with the MODIS data, we see that humans are also contributing.”

- China’s outsized contribution to the global greening trend comes in large part from its programs to conserve and expand forests (about 42 percent of the greening contribution). These programs were developed in an effort to reduce the effects of soil erosion, air pollution, and climate change.

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Figure 37: Over the last two decades, the Earth has seen an increase in foliage around the planet, measured in average leaf area per year on plants and trees. Data from NASA satellites shows that China and India are leading the increase in greening on land. The effect stems mainly from ambitious tree planting programs in China and intensive agriculture in both countries (image credit: NASA Earth Observatory, image by Joshua Stevens, using data courtesy of Chen et al., (2019). Story by Abby Tabor, NASA Ames Research Center, with Mike Carlowicz, Earth Observatory)

- Another 32 percent of the greening change in China, and 82 percent in India, comes from intensive cultivation of food crops. The land area used to grow crops in China and India has not changed much since the early 2000s. Yet both countries have greatly increased both their annual total green leaf area and their food production in order to feed their large populations. The agricultural greening was achieved through multiple cropping practices, whereby a field is replanted to produce another harvest several times a year. Production of grains, vegetables, fruits and more have increased by 35 to 40 percent since 2000.

- How the greening trend may change in the future depends on numerous factors. For example, increased food production in India is facilitated by groundwater irrigation. If the groundwater is depleted, this trend may change. The researchers also pointed out that the gain in greenness around the world does not necessarily offset the loss of natural vegetation in tropical regions such as Brazil and Indonesia. There are consequences for sustainability and biodiversity in those ecosystems beyond the simple greenness of the landscape.

- Nemani sees a positive message in the new findings. “Once people realize there is a problem, they tend to fix it,” he said. “In the 1970s and 80s in India and China, the situation around vegetation loss was not good. In the 1990s, people realized it, and today things have improved. Humans are incredibly resilient. That’s what we see in the satellite data.”

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Figure 38: This map shows the increase or decrease in green vegetation—measured in average leaf area per year—in different regions of the world between 2000 and 2017. Note that the maps of Figures 37 and 38 are not measuring the overall greenness, which explains why the Amazon and eastern North America do not stand out, among other forested areas (image credit: NASA Earth Observatory, image by Joshua Stevens, using data courtesy of Chen et al., (2019). Story by Abby Tabor, NASA Ames Research Center, with Mike Carlowicz, Earth Observatory)

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Figure 39: Ambitious tree-planting programs and intensified agriculture have led to more land area covered in vegetation ((image credit: NASA Earth Observatory, image by Joshua Stevens, using data courtesy of Chen et al., (2019). Story by Abby Tabor, NASA Ames Research Center, with Mike Carlowicz, Earth Observatory)

• February 6, 2019: For the ranchers and soybean farmers of northwestern Argentina, January 2019 was a remarkably wet month. 32)

- After several weeks of storms that dropped about five times more rain than usual, floods have inundated millions of hectares of farmland, forced thousands of people to evacuate, and even turned some unsuspecting cattle into swimmers. Some areas received a year’s worth of rain in the first two weeks of January, according to the Buenos Aires Times.

- The flooding has caused more than $2 billion in agricultural damage, according to one estimate. That makes it Argentina’s second-most-expensive flood on record.

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Figure 40: This MODIS image shows the flooding along the Paraná River on 4 February 2019, composed in false color, using a combination of infrared and visible light (MODIS bands 7-2-1). Flood water appears black; vegetation is bright green (image credit: NASA Earth Observatory image by Lauren Dauphin, using MODIS data from NASA EOSDIS/LANCE and GIBS/Worldview. Story by Adam Voiland)

• February 1, 2019: While much of North America is enduring exceptionally cold winter temperatures, Australia is coping with all-time record summer heat. 33)

- An unusual, prolonged period of heatwaves has been sweeping over Australia for most of the summer, including the country's hottest December on record. The intense heat has caused numerous deaths, power outages, and severe fires. The heatwaves started in late November when Queensland saw record-breaking temperatures on the north tropical and central coasts.

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Figure 41: This map shows land surface temperature anomalies from January 14-28, 2019. Red colors depict areas that were hotter than average for the same two-week period from 2000-2012; blues were colder than average. White pixels were normal, and gray pixels did not have enough data, most likely due to excessive cloud cover. This temperature anomaly map is based on data from MODIS on NASA’s Terra satellite (image credit: NASA Earth Observatory, image by Lauren Dauphin, using data from the Level 1 and Atmospheres Active Distribution System (LAADS) and Land Atmosphere Near real-time Capability for EOS (LANCE). Story by Kasha Patel)

- Note that the map depicts LSTs (Land Surface Temperatures), not air temperatures. LSTs reflect how hot the surface of the Earth would feel to the touch and can sometimes be significantly hotter or cooler than air temperatures. (To learn more about land surface temperatures and air temperatures, read: Where is the Hottest Place on Earth?).

- The summer of 2018-19 has brought seven of the ten hottest days on record for Australia. The most potent heatwave so far occurred from January 11-18, when nationally averaged mean temperatures exceeded 40°C (104°F) for five days in a row. Nationally, January 15th ranked as the second-warmest day ever in Australia, falling 0.02°C short of the all-time record from January 2013. Adelaide recorded the hottest temperature for any Australian state capital in 80 years, reaching 46.4°C (116°F) on January 25.

- A few factors have contributed to the severe summer, starting with a dearth of strong weather fronts that would typically cool the country. In summer, sunlight heats the Australian landmass more quickly than the surrounding ocean. This difference in heating usually draws in moist air over northern Australia, which gradually brings about westerly winds that bring in cooler and rainy conditions with the monsoon.

- But this summer the rains didn't develop. Weather patterns in northern Australia were largely static, providing no significant weather systems to clear out the persistent hot air mass. The city of Darwin usually experiences the beginning of the monsoon in late December, but as of January 22, rainy patterns still had not set in. Western Australia also experienced sparse thunderstorms and no monsoonal activity in December. Northwesterly winds and various weather systems dragged hot air east and south across the Northern Territory, South Australia, western Queensland, New South Wales, and Victoria.

- The increased temperatures are a continuation of a longer warming trend for Australia. Twenty of the warmest years on record have occurred in the past 22 years; the last four have been the hottest on record. Throughout 2018, maximum temperatures for each month were above the country’s average.

• January 30, 2019: Desperately cold weather is now gripping the Midwest and Northern Plains of the United States, as well as interior Canada. The culprit is a familiar one: the polar vortex. 34)

- A large area of low pressure and extremely cold air usually swirls over the Arctic, with strong counter-clockwise winds that trap the cold around the Pole. But disturbances in the jet stream and the intrusion of warmer mid-latitude air masses can disturb this polar vortex and make it unstable, sending Arctic air south into middle latitudes.

- That has been the case in late January 2019. Forecasters are predicting that air temperatures in parts of the continental United States will drop to their lowest levels since at least 1994, with the potential to break all-time record lows for January 30 and 31. With clear skies, steady winds, and snow cover on the ground, at least 90 million Americans could experience temperatures at or below zero degrees Fahrenheit (-18° Celsius), according to the U.S. National Weather Service (NWS).

- Figure 42 is not a traditional forecast, but a reanalysis of model input fixed in time—a representation of atmospheric conditions near dawn on January 29, 2019. Measurements of temperature, moisture, wind speeds and directions, and other conditions are compiled from NASA satellites and other sources, and then added to the model to closely simulate observed reality. Note how some portions of the Arctic are close to the freezing point—significantly warmer than usual for the dark of mid-winter—while masses of cooler air plunge toward the interior of North America.

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Figure 42: This map shows air temperatures at 2 meters above ground at 09:00 Universal Time (4 a.m. Eastern Standard Time) on January 29, 2019, as represented by the Goddard Earth Observing System Model, Version 5. GEOS-5 is a global atmospheric model that uses mathematical equations run through a supercomputer to represent physical processes (image credit: NASA Earth Observatory, image by Joshua Stevens, using GEOS-5 data from the Global Modeling and Assimilation Office at NASA GSFC, Story by Michael Carlowicz)

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Figure 43: You can almost feel that cold in this natural-color image, acquired on January 27, 2019, by MODIS (Moderate Resolution Imaging Spectroradiometer) on NASA’s Terra satellite. Cloud streets and lake-effect snow stretch across the scene, as frigid Arctic winds blew over the Great Lakes (image credit: NASA Earth Observatory, image by Joshua Stevens, using MODIS data from NASA EOSDIS/LANCE and GIBS/Worldview. Story by Michael Carlowicz)

- NWS meteorologists predicted that steady northwest winds (10 to 20 miles per hour) were likely to add to the misery, causing dangerous wind chills below -40°F (-40°C) in portions of 12 states. A wind chill of -20°F can cause frostbite in as little as 30 minutes, according to the weather service.

- Meteorologists at The Washington Post pointed out that temperatures on 31 January 2019, in the Midwestern U.S. will be likely colder than those on the North Slope of Alaska.

Figure 44: Animated AIRS image of the polar vortex moving from Central Canada into the U.S. Midwest from January 20 through January 29. The illustration shows temperatures at an altitude of about 300-500 m above the ground. The lowest temperatures are shown in purple and blue and range from -40 degrees Fahrenheit (also -40 degrees Celsius) to -10ºF (-23ºC). As the data series progresses, you can see how the coldest purple areas of the air mass scoop down into the U.S. (image credit: NASA/JPL-Caltech AIRS Project) 35)

• December 23, 2018: Spring and summer are bloom times for plants on land; they are also bloom times for plant-like organisms in the ocean. Fueled by the abundant sunshine of midsummer, phytoplankton were recently spied blooming off the coast of Argentina. 36)

- The plant-like floating organisms of Figure 45 form the center of the ocean food web, becoming food for everything from microscopic animals (zooplankton) to fish to whales. They are key producers of the oxygen that makes the planet livable for humans and other creatures. And they are critical to the global carbon cycle, as they absorb carbon dioxide from the atmosphere and turn it into carbohydrates. When the phytoplankton die (or animals eat and excrete them), some of the remains sink, carrying carbon to the bottom of the ocean.

- The milky green and blue bloom developed along the continental shelf, where warmer, saltier coastal waters and currents from the subtropics meet the colder, fresher waters flowing from the south. Where these currents collide—known to oceanographers as a shelf-break front—turbulent eddies and swirls form, pulling nutrients up from the deep ocean.

- The aquamarine stripes and swirls are coccolithophores, a type of phytoplankton with microscopic calcite shells that can give water a chalky color. The various shades of green are probably a mix of diatoms, dinoflagellates, and other species. Previous ship-based studies of the region have shown that Emiliania huxleyi coccolithophores and Prorocentrum sp. dinoflagellates tend to dominate. Scientists are working to identify types of phytoplankton from satellite images; hyperspectral imagers planned for future satellite missions should make that easier.

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Figure 45: The MODIS instrument on NASA's Terra satellite captured a natural-color image (above left) of the bloom on December 17, 2018. The right image shows Terra observations of concentrations of chlorophyll-a, the pigment used by phytoplankton to harness sunlight and turn it into food (image credit: NASA Earth Observatory, image by Joshua Stevens, using MODIS data from NASA EOSDIS/LANCE and GIBS/Worldview, and NASA's OceanColor Web. Story by Mike Carlowicz)

• December 15, 2018: Though the United States and Cuba have operated in largely separate economic spheres for decades, they are only separated by 150 kilometers (90 miles). On December 2, 2018, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this image of the narrow, watery boundaries that separate the United States, Cuba, and the Bahamas. 37)

- From space, the deep water of the Florida Strait appears dark blue in comparison to the shallower, turquoise water covering the Cay Sal Bank and Bahama Banks. Both of these platforms formed as carbonate minerals—produced by certain types of bacteria and sea organisms—were deposited on the ocean floor over millions of years.

- Undeveloped ecosystems (forests and wetlands) cover 53 percent of Cuba, according to an analysis of recent Landsat imagery. About 40 percent of the island’s land surface is used for agriculture. Major crops include cassava, tobacco, grapefruit, and sugar. Reservoirs cover about 1 percent of the island’s land surface, and cities cover less than 1 percent.

- Despite the patchwork of farmland and pastures, Cuba is known for having relatively large stretches of pristine mangrove forests and undisturbed coral reefs, beaches, and sea grass marshes.

- “Cuba is an ecological rarity in Latin America and the Caribbean region,” said University of Vermont remote sensing scientist Gillian Galford in a 2018 report. “Its complex political and economic history shows limited disturbances, extinctions, pollution, and resource depletion.”

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Figure 46: MODIS image of Cuba acquired on 2 December 2018. Civilization’s footprint on this Caribbean island has been relatively light (image credit: NASA Earth Observatory image by Joshua Stevens, using MODIS data from NASA EOSDIS/LANCE and GIBS/Worldview. Story by Adam Voiland)

• November 28, 2018: The 2018 fire season in California has been record-breaking. The Mendocino Complex in July was California’s largest fire by burned area on record, destroying nearly half a million acres. The Camp Fire in November was the deadliest and most destructive in state history, completely wiping out the town of Paradise. 38)

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Figure 47: This image shows the charred land—known as a burn scar—from the Camp Fire, which has destroyed more than 18,000 structures and caused at least 85 deaths. The fire, which has burned more than 153,000 acres, is now fully contained, according to the California Department of Forestry and Fire Protection. This image was acquired by MODIS on NASA’s Terra satellite on 25 November 2018 (image credit: NASA Earth Observatory, image by Lauren Dauphin, using MODIS data from NASA EOSDIS/LANCE and GIBS/Worldview. Story by Kasha Patel)

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Figure 48: A wide view of Northern California, where burn scars from nine major 2018 fires are visible from space. The image was acquired by Terra MODIS on November 25, 2018 (image credit: NASA Earth Observatory, image by Lauren Dauphin, using MODIS data from NASA EOSDIS/LANCE and GIBS/Worldview. Story by Kasha Patel)

- “Every year, we keep hearing fires labeled as ‘the biggest’, ‘worst’, and ‘deadliest’,” said Amber Soja, a wildfire scientist at NASA’s Langley Research Center. “We keep hearing that this is the ‘new normal.’ Hopefully it’s not true for long, but right now it is.”

- California’s fire activity in 2018 is part of a longer trend of larger and more frequent fires in the western United States. Of the total area burned in the West since 1950, 61 percent of it has occurred in the past two decades, according to Keith Weber, GIS Director at Idaho State University and principal investigator of the NASA project RECOVER. “The 2018 fire year is going to fit right in to what's been going on the last decade or two. In fact, it might be a taller spike in the overall trend.”

- High temperatures, low relative humidity, high wind speed, and scarce precipitation have increased dryness and made live and dead vegetation in western forests easier to burn. “Those fire conditions all fall under weather and climate,” said Soja. “The weather will change as Earth warms, and we’re seeing that happen.”

- Soja also noted that California had a really wet winter in 2017, which helped build up grass and brush in rural and forested areas. The vegetation was an abundant fuel source as California headed into the 2018 dry season, which was exceptionally dry and lasted into late October.

- As fires are becoming more numerous and frequent, NASA’s Disasters Program has been working with disaster managers to respond to the blazes. For California’s Camp Fire and Woolsey Fire, NASA scientists and satellite analysts have been producing maps and damage assessments of the burned areas, including identifying areas that will be more susceptible to landslides in the upcoming winter.

• November 13, 2018: California continues to be plagued by wildfires — including the Woolsey Fire near Los Angeles and the Camp Fire in Northern California, now one of the deadliest in the state's history. NASA satellites are observing these fires — and the damage they're leaving behind — from space. 39)

- The Advanced Rapid Imaging and Analysis (ARIA) team at NASA's Jet Propulsion Laboratory in Pasadena, California, produced new damage maps using synthetic aperture radar images from the Copernicus Sentinel-1 satellites. The map of Figure 49 shows areas likely damaged by the Woolsey Fire as of Sunday, Nov. 11. It covers an area of about 50 miles by 25 miles (80 km by 40 km) — framed by the red polygon. The color variation from yellow to red indicates increasing ground surface change, or damage.

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Figure 49: The ARIA (Advanced Rapid Imaging and Analysis) team at NASA/JPL in Pasadena, California, created these DPMs (Damage Proxy Maps) depicting areas in California likely damaged by the Woolsey and Camp Fires (image credit: NASA/JPL)

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Figure 50: This map shows damage from the Camp Fire in Northern California as of Saturday, Nov. 10. It depicts an area of about 55 miles by 48 miles (88 km by 77 km) and includes the city of Paradise, one of the most devastated areas. Like the previous map, red areas show the most severe surface change, or damage. The ARIA team compared the data for both images to the Google Crisismap for preliminary validation (image credit: NASA/JPL)

• On November 8, 2018, the Camp Fire erupted 90 miles (140 km) north of Sacramento, CA. As of 10 a.m. PST on Nov. 9, the fire had consumed 70,000 acres of land and was 5 percent contained, or surrounded by a barrier. 40)

- Strong winds pushed the fire to the south and southwest overnight, tripling its size and spreading smoke over the Sacramento Valley. The Moderate Resolution Imaging Spectrometer (MODIS) on NASA's Terra satellite captured the natural-color image (annotate above, unannotated at right) on Nov. 9. The High-Resolution Rapid Refresh Smoke model, using data from National Oceanic and Atmospheric Administration (NOAA) and NASA satellites, shows the smoke should continue to spread west. The image also shows two more fires in southern California, the Hill and Woolsey Fires.

- More than 2,000 personnel have been sent to fight the Camp Fire, which is predicted to be fully contained by Nov. 30. Firefighters are having difficulty containing it due to strong winds, which fan the flames and carry burning vegetation downwind. The area also has heavy and dry fuel loads, or flammable material.

- State and local officials have closed several major highways, including portions of Highway 191. They also ordered evacuations in several towns, including Concow and Paradise, where the fatal fire burned through the town.

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Figure 51: Annotated image of the Camp Fire in Northern California and the Hill and Woolsey fires in southern California, taken Nov. 9, 2018, by the MODIS instrument on NASA's Terra satellite (image credit: NASA Earth Observatory)

On 6 October 2018, NASA’s Terra satellite completed 100,000 orbits around Earth. Terra joins a handful of satellites to mark this orbital milestone, including the ISS (International Space Station), ERBS (Earth’s Radiation Budget Satellite), Landsat-5 and Landsat-7. Terra, which launched Dec. 18, 1999, is projected to continue operation into the 2020s. 41)

- The five scientific instruments aboard Terra provide long-term value for advancing scientific understanding of our planet — one of the longest running satellite climate data records — and yield immediate benefits in such areas as public health. For example, recently scientists analyzed 15 years of pollution data in California, collected by the MISR (Multi-angle Imaging Spectroradiometer) instrument, and discovered that the state’s clean air programs have been successful in reducing particle pollution. More urgently, data from the ASTER (Advanced Spaceborne Thermal Emission and Reflection) radiometer and MISR provided crucial information about the air quality and land change conditions around Hawaii’s erupting Kilauea volcano, informing critical public health and safety decisions.

- But just as a plane can’t fly without a crew, the Terra satellite never could have provided these vital benefits to society for this long without decades of dedicated work by engineers and scientists.

- Completing more than 2.5 billion miles of flight around Earth over almost 19 years, by a satellite designed to operate for five years, does not happen unless a satellite is designed, constructed and operated with great care.

- “Multiple, different aspects in the team make it work,” said Eric Moyer, deputy project manager ­– technical at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “The Terra team includes flight operations, subsystem engineers, subject matter experts, the instrument teams and the science teams for each of the instruments. Overall it all has to be coordinated, so one activity doesn’t negatively impact another instrument,” said Moyer, who worked on Terra during construction and continues to be involved with its operations today.

- Dimitrios Mantziaras, Terra mission director at Goddard, summed up what it takes: “A well-built spacecraft, talented people running it and making great science products, with lots of people using the data, that’s what has kept Terra running all these years.”

- Designing a Pioneer: Terra was unique from the beginning. It was one of the first satellites to study Earth system science, and the first to look at land, water and the atmosphere at the same time. Unlike many previous, smaller satellites, Terra didn’t have a previously launched satellite platform to build upon. It had to be designed from scratch.

- “Unlike the Landsat mission series, which continues to improve upon its original design, nothing like Terra had ever been built,” said Dick Quinn, Terra’s spacecraft manufacturing representative from Lockheed Martin, who still works part-time with the team responsible for Terra’s continued flight.

- Terra was meant to be the first in a series of satellites, known as AM-1, 2 and 3, each with a design life of about five years. Instead, the mission team ended up designing a satellite that lasted longer than the combined design life of three generations of Terra satellites.

- Constructing and Operating a Solid Satellite: The built-in redundancies and flexibility of the satellite were put to the test in 2009, when a micrometeoroid struck a power cell, degrading the thermal control for the battery.

- “We had to change the way we manage the battery to keep it operating efficiently and keep it at the right temperature,” said Jason Hendrickson, Terra flight systems manager at Goddard, who joined the team in 2013. To do this, the team used the charge and discharge cycle of the battery itself to generate the heat necessary to keep the battery operating. They have been finetuning this cycle ever since.

- Terra engineers and scientists continually plan for worst-case scenarios, anticipating problems that may never develop. “We are always thinking, if this were to fail, how are we going to respond?” Hendrickson said. “You can’t just go to the garage and swap out parts.”

- Not only does the team plan for many possible scenarios, but it also looks back at the response and figures out how it can be improved. However, most of the time, they don’t have to wait for a system failure to practice contingency plans. For example, in 2017 the team executed the second lunar deep space calibration maneuver in Terra’s lifetime. The satellite turned to look at deep space, instead of at Earth. “We had to take into account what would happen if the computer were to fail when we were pointed at deep space,” Hendrickson said.

- The calibration maneuver was executed successfully and the team never had to conduct their contingency plan. The science gained from calibrating Terra’s data against deep space allowed the scientists to improve the data collected by the ASTER instrument. ASTER, a collaborative instrument with Japan and the United States, is one of five instruments on Terra. It monitors volcanic eruptions, among many other objectives and provides high resolution imagery of locations all over the world.

- In addition to ASTER, the instruments on Terra make many contributions and benefit people worldwide:

a) The Moderate Imaging Spectroradiometer (MODIS) collects data on land cover, land and sea surface temperatures, aerosol particle properties and cloud cover changes. For example, MODIS data is used to protect people’s lives and property through operations like MODIS rapid response, which monitors wildfires daily.

b) MISR continues to provide data useful for health researchers studying the effects of particulate matter on populations all over the world, as well as fundamental studies of how aerosol particles and clouds affect weather and climate and investigations of terrestrial ecology.

c) Measurements of Pollution in the Troposphere (MOPITT), a collaboration with the Canadian Space Agency, is used to study carbon monoxide in the atmosphere, an indicator of pollution concentrations, also a contributor to global health issues.

d) Clouds and Earth’s Radiant Energy System (CERES) provides data on Earth’s energy budget, helping monitor the outgoing reflected solar and emitted infrared radiation of the planet.

- The science teams for each instrument work with the operations and technical teams to ensure that the scientific data provided is accurate and useful to the researchers who access it.

- The data is free and is valued by people all over the world. Not only can it be accessed daily, there are over 240 direct broadcast sites, where data can be downloaded in near real-time, all over the world. Moyer said that one of the most rewarding parts of working with Terra is that “the science data is truly valued by people we don’t even know. People all over the world.”

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Figure 52: Terra’s test team stands in front of the satellite during its construction and testing phase (image credit: NASA, Dick Quinn)

• September 13, 2018: NASA's Multi-angle Imaging SpectroRadiometer (MISR) passed over Hurricane Florence as it approached the eastern coast of the United States on Thursday, September 13, 2018. At the time the image was acquired, Florence was a large Category 2 storm and coastal areas were already being hit with tropical-storm-force winds. 42)

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Figure 53: These data were captured during Terra orbit 99670. The MISR instrument, flying onboard NASA's Terra satellite, carries nine cameras that observe Earth at different angles. It takes about seven minutes for all the cameras to observe the same location. This stereo anaglyph shows a 3D view of Florence. You will need red-blue 3D glasses, with the red lens placed over the left eye, to view the effect. The anaglyph shows the high clouds associated with strong thunderstorms in the eyewall of hurricane and individual strong thunderstorms in the outer rain bands. These smaller storms can sometimes spawn tornadoes (image credit: NASA/JPL).

• August 24, 2018: Instruments on NASA's Terra and Aqua satellites were watching as Hurricane Lane — a category 2 storm as of Friday, Aug. 24 — made its way toward Hawaii. 43)

- NASA's MISR (Multi-angle Imaging SpectroRadiometer) captured images of Lane on just before noon local time on 24 August. MISR, flying onboard NASA's Terra satellite, carries nine cameras that observe Earth at different angles. It takes approximately seven minutes for all the cameras to observe the same location, and the motion of the clouds during that time is used to compute the wind speed at the cloudtops.

- The image shows the storm as viewed by the central, downward-looking camera. Also included is a stereo anaglyph, which combines two of the MISR angles to show a three-dimensional view of Lane (Figure 54). The image has been rotated in such a way that north is at the bottom. You will need red-blue glasses to view the anaglyph (with the red lens placed over your left eye).

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Figure 54: Stereo anaglyph using MISR data. The image shows a 3D view of Hurricane Lane on August 24. Red-blue 3D glasses required (image credit: NASA/GSFC/LaRC/JPL-Caltech, MISR Team)

- NASA's AIRS (Atmospheric Infrared Sounder) captured Hurricane Lane when the Aqua satellite passed overhead on 22 and 23 August (Figure 55). The infrared imagery represents the temperatures of cloud tops and the ocean surface. Purple shows very cold clouds high in the atmosphere above the center of the hurricane, while blue and green show the warmer temperatures of lower clouds surrounding the storm center. The orange and red areas, away from the storm, have almost no clouds, and the ocean shines through. In the 22 August image, a prominent eye is also visible. No eye is visible on the Aug. 23 image, either because it was too small for AIRS to detect or it was covered by high, cold clouds.

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Figure 55: This image shows Hurricane Lane as observed by the AIRS instrument on NASA's Aqua satellite on Thursday, 23 August (image credit: NASA/JPL-Caltech)

• August 15, 2018: When lightning storms passed over the Canadian province of British Columbia in July and August 2018, they ignited several hundred fires in forests that were already primed to burn. Abnormally hot, dry weather had stressed vegetation and parched the soil. And infestations of mountain pine beetles had left many forests with large numbers of dead trees. 44)

- Plumes of wildfire smoke can have a significant impact on people and the environment. Small particles in smoke pose a health risk because they can easily enter the lungs and bloodstream. And dark particles in smoke can land on snow and ice and accelerate melting by absorbing heat and reducing the reflectivity of the surface.

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Figure 56: MODIS on Terra captured this image of British Columbia’s smoky landscape on August 13, 2018. Some of the thickest smoke lingered in the valleys, but plumes had also spread well beyond the province into Washington state and deep into the U.S. Midwest (image credit: NASA Earth Observatory, image by Lauren Dauphin using MODIS data from LANCE/EOSDIS Rapid Response, story by Adam Voiland)

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Figure 57: OLI (Operational Land Imager) on Landsat-8 captured this natural-color image of smoke lingering in valleys near the snow-capped peaks of the Coast Mountains on August 7, 2018 (image credit: NASA Earth Observatory image by Lauren Dauphin using Landsat data from the U.S. Geological Survey, story by Adam Voiland)

• August 11, 2018: Every austral winter in the central Andes, fresh snowfall covers and fills the gaps between mountaintops that have more permanent snow and ice. The continuous strip of winter white is visible in this image, acquired on July 30, 2018, with the MODIS (Moderate Resolution Imaging Spectroradiometer) on NASA’s Terra satellite. 45)

- Not all parts of the mountain range—one of the longest in the world—see equal amounts of the seasonal white stuff. The Andes span about 7,200 kilometers (4,500 miles) along the western side of South America, passing through multiple climate regions from dry to wet. This image shows a part of the Andes in central Chile and Argentina that bridges the two climate zones.

- Research into snowfall patterns has found that the largest areas of snow cover have occurred in this central zone. Areas to the north tend to be limited by a drier climate, while areas to the south are limited by the range’s lower elevations. In this image you can see the Aconcagua, the highest mountain in the Southern Hemisphere, rising 6,962 meters (22,841 feet) above sea level.

- In this part of the range, the west side tends to receive more precipitation during austral winter, from June through August, when moist air from the Pacific Ocean is carried inland by westerly winds. But winter storms that pass through—including one in early August—can deliver enough snow to fully blanket glaciers on both sides.

- The snowpack that accumulates in the mountains is the primary source of water for communities at lower altitudes. Streams deliver the melt water to populated areas of central-western Argentina and central Chile, where it is particularly important for cities’ water supply, power generation, and agriculture. According to Gonzalo Barcaza of the General Water Directorate in Santiago, Chile, this winter has been drier than usual and follows nearly a decade of drought.

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Figure 58: MODIS image acquired on 30July 2018 showing the snow coverage in the Andes region (image credit: NASA Earth Observatory, image by Lauren Dauphin, using MODIS data from LANCE/EOSDIS Rapid Response, story by Kathryn Hansen)

• August 2018: The nearly 20 years of MODIS imagery is the longest continuous daily global satellite observation record of Earth ever compiled. As of June 2018, all daily global MODIS imagery dating back to the operational start of MODIS data collection in 2000 is available through NASA’s (GIBS Global Imagery Browse Services). GIBS was established by NASA’s Earth Observing System Data and Information System (EOSDIS) in 2011 and provides quick access to over 700 satellite imagery products covering every part of the world. 46)

- The Worldview tool from NASA's Earth Observing System Data and Information System (EOSDIS) provides the capability to interactively browse over 600 global, full-resolution satellite imagery layers and then download the underlying data. Many of the imagery layers are updated within three hours of observation, essentially showing the entire Earth as it looks "right now". This supports time-critical application areas such as wildfire management, air quality measurements, and flood monitoring. View current natural hazards and events using the Events tab which reveals a list of natural events, including wildfires, tropical storms, and volcanic eruptions. Animate the imagery over time. Arctic and Antarctic views of several products are also available for a "full globe" perspective. Browsing on tablet and smartphone devices is generally supported for mobile access to the imagery.

- Worldview uses NASA's GIBS (Global Imagery Browse Services) to rapidly retrieve its imagery for an interactive browsing experience. While Worldview uses OpenLayers as its mapping library, GIBS imagery can also be accessed from Google Earth, NASA WorldWind, and several other clients. We encourage interested developers to build their own clients or integrate NASA imagery into their existing ones using these services.

• July 31, 2018: The Carr Fire, which has been burning near Redding, California since July 23, spanned 110,154 acres (44,578 hectares) as of July 31 and was 27 percent contained. The Ferguson Fire, near Yosemite National Park, spanned 57,846 acres (23,409 hectares) as of July 31 and was 33 percent contained (Figure 59). 47)

- These data were acquired during Terra orbit 98973 and 99002. The smoke plume height calculation was performed using the MISR INteractive eXplorer (MINX) software tool, which is publicly available at https://github.com/nasa/MINX. The MISR Plume Height Project maintains a database of global smoke plume heights, accessible at https://www-misr.jpl.nasa.gov/getData/accessData/MisrMinxPlumes2/.

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Figure 59: The MISR (Multi-angle Imaging SpectroRadiometer) instrument on NASA's Terra satellite took these images of the Carr Fire (left) and the Ferguson Fire (right) on July 27 and July 29, respectively (image credit: NASA)

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Figure 60: Left: This image shows the Carr Fire near Redding California on July 27 as observed by NASA's MISR instrument. The angular information from MISR's images is used to calculate the height of the smoke plume. The results are superimposed on the image on the right (image credit: NASA)

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Figure 61: The left image shows the Ferguson Fire near Yosemite National Park on July 29 as observed by NASA's MISR instrument. The angular information from MISR's images is used to calculate the height of the smoke plume. The results are superimposed on the image on the right (image credit: NASA)

• July 26, 2018: Hawaii's Kilauea volcano continues to create new land as flows from fissure 8, one of the most active to break ground since the eruption began in early May, reach the ocean. The ASTER (Advanced Spaceborne Thermal Emission and Reflection) radiometer instrument on NASA's Terra satellite detected the lava flow of fissure 8 — which extends from Leilani Estates to the Pacific Ocean — on July 25. 48)

- With its 14 spectral bands from the visible to the thermal infrared wavelength region and its high spatial resolution of about 15 to 90 m, ASTER images Earth to map and monitor the changing surface of our planet. ASTER is one of five Earth-observing instruments launched Dec. 18, 1999, on Terra. The instrument was built by Japan's METI (Ministry of Economy, Trade and Industry). A joint U.S./Japan science team is responsible for validation and calibration of the instrument and data products.

- The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping and monitoring of dynamic conditions and temporal change. Example applications are monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance.

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Figure 62: In this image, vegetation is displayed in red, clouds are white and the hot lava flows, detected by ASTER's thermal infrared channels, are overlaid in yellow. The image covers an area of 15.3 x 18.6 kilometers (image credit: NASA/METI/AIST/Japan Space Systems, and U.S./Japan ASTER Science Team)

• July 21, 2018: Scorching, dry conditions are spurring historic wildfire outbreaks across Sweden this summer. On July 19, 2018, more than 40 fires dotted the country, causing firefighters to scramble and hundreds of people to evacuate their homes. The Swedish government called for international assistance—the second time this summer—and received firefighting airplanes and helicopters from Italy and Norway. 49)

- The intense fires are unusual for this time of the year, as Sweden's summers are normally mild. In May 2018, several cities experienced their hottest May days in 150 years of recordkeeping. Temperatures cooled off in June, but returned to record highs in July, when Sweden’s national weather agency issued a warning for extremely high temperatures. At the same time, Sweden has experienced very low rainfall this summer.

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Figure 63: This natural-color image was acquired by MODIS on NASA’s Terra satellite on July 17, 2018. The largest fire was near Ljusdal, although Kårböle, Jämtland, and several towns have been evacuated due to fires. No fatalities have been reported so far. The Copernicus Atmosphere Monitoring Service forecast model shows an increase in fine particulate pollution above the fire-stricken areas this week (image credit: NASA Earth Observatory image by Lauren Dauphin and Joshua Stevens, using MODIS data from LANCE/EOSDIS Rapid Response and the Level 1 and Atmospheres Active Distribution System (LAADS). Story by Kasha Patel)

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Figure 64: This temperature anomaly map is based on data from MODIS on NASA’s Terra satellite. It shows land surface temperatures from July 1-15, 2018, compared to the 2000–2015 average for the same two-week period. Red colors depict areas that were hotter than average; blues were colder than average. White pixels were normal, and gray pixels did not have enough data, most likely due to excessive cloud cover. Note that it depicts land surface temperatures, not air temperatures. Land surface temperatures reflect how hot the surface of the Earth would feel to the touch in a particular location. They can sometimes be significantly hotter or cooler than air temperatures (image credit: NASA Earth Observatory image by Lauren Dauphin and Joshua Stevens, using MODIS data from LANCE/EOSDIS Rapid Response and the Level 1 and Atmospheres Active Distribution System (LAADS). Story by Kasha Patel)

- The hot, dry conditions helped create the severe fire risk for the Sweden. As of July 20, Sweden has over 10,000 hectares of burned land, which is nearly 24 times higher than the amount of burned land averaged over 2008-2017, according to the Copernicus Emergency Management Service.

- High temperatures and wildfires are also hitting neighboring countries and as far north as the Arctic circle. All-time high temperatures were hit in 14 locations in Norway, including Troms county where temperatures hit 33°C, as the southern part of the country was peppered with fires in 100 localities last week. Northern Finland saw temperatures of 33°C on July 18, while wildfires also spread near the border of Finland and Russia (Figure 65).

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Figure 65: This natural-color image shows fires near the Russia-Finland border. The image was captured by MODIS on NASA’s Aqua satellite on July 20, 2018 (image credit: NASA Earth Observatory image by Lauren Dauphin and Joshua Stevens, using MODIS data from LANCE/EOSDIS Rapid Response and the Level 1 and Atmospheres Active Distribution System (LAADS). Story by Kasha Patel)

• July 7, 2018: Northeast of Africa’s Kalahari Desert and southeast of the Okavango Delta lies one of the largest salt pans in the world. It was once the site of one of the largest inland seas on Earth. 50)

- For much of the year, the salt pans glimmer in white, parched by the sun and the salt and allowing little more than algae to grow. But during the rainy season (roughly November to March), the area can be transformed into a crucial wetland. Water can flow in from the Boteti and Nata rivers, filling ephemeral ponds, watering holes, and shallow lakes and creating short-lived but abundant grasslands. The event draws migrating wildebeest and zebras, as well as the predators that hunt them. The waters fill with ducks, geese, pelicans, and flamingos—one of just two breeding spots in southern Africa for the long-legged birds.

- The pans are the salty remains of ancient Lake Makgadikgadi. Scientists estimate that the inland sea once spanned anywhere from 80,000 to 275,000 km2. The Okavango, Zambezi, and Cuando rivers likely emptied into this lake until tectonic shifts changed the elevation of the landscape and a changing climate dried up the rains.

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Figure 66: On June 10, 2018, the MODIS instrument on NASA’s Terra satellite acquired this natural-color image of the Makgadikgadi Salt Pans. The collection of salt flats covers roughly 30,000 km2 amidst desert and dry savanna in Botswana. Located in Makgadikgadi National Park and Nxai Pan National Park, the salt pans are rivaled in extent only by the Salar de Uyuni in Bolivia (image credit: NASA Earth Observatory, image by Joshua Stevens, using MODIS data from LANCE/EOSDIS Rapid Response, story by Mike Carlowicz)

• June 5, 2018: Powerful Earth-observing instruments aboard NASA's Terra and Aqua satellites, launched in 1999 and 2002, respectively, have observed nearly two decades of planetary change. Now, for the first time, all that imagery—from the first operational image to imagery acquired today—is available for exploration in Worldview. 51) 52)

Thanks to the efforts of several NASA teams, the public can now interactively browse all global imagery from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument quickly and easily from the comfort of a home computer. All global MODIS imagery dating back to the operational start of MODIS in 2000 is available through NASA's GIBS (Global Imagery Browse Services) for viewing using NASA's Worldview application. And there's a lot to see.

This achievement is the result of more than a half-decade of work and represents the longest continuous daily global satellite observation record of Earth ever compiled. For researchers, the ability to rapidly access and explore all MODIS global imagery greatly improves their use of these data.

"In the '80s and '90s, if you wanted to look at, say, clouds off the coast of California, you had to figure out the time of year when it was best to look at these clouds, then place a data request for a specific window of days when you thought the satellite overflew the area," says Santiago Gassó, an associate research scientist with NASA's Goddard Earth Sciences Technology And Research program at Morgan State University, Baltimore. "You would get a physical tape with these images and have to put this into the processing system. Only then would you know if the image was usable. This process used to take from days to weeks. Now, you can look at images for days, weeks and even years in a matter of minutes in Worldview, immediately find the images you need, and download them for use. It's fantastic!"

Daily MODIS global images have been produced since the public debut of Worldview in 2012. But data users wanted more. "Users said to us, 'We know you have the source data available, and we'd like to see it as imagery in Worldview,'" says Ryan Boller, the EOSDIS data visualization lead and Worldview Project owner.

GIBS provides access to more than 600 satellite imagery products covering every part of the world. Worldview pulls imagery from GIBS and allows users to interactively overlay all of these data products on top of a MODIS global base map from Terra or Aqua. Worldview users can even create data animations at the touch of a button and easily share imagery. Both GIBS and Worldview are part of NASA's EOSDIS (Earth Observing System Data and Information System), which provides end-to-end capabilities for managing NASA Earth-observing data.

The completion of this effort gives NASA's worldwide audience the ability to interactively view their world their way and interactively explore almost 20 years of planetary change. As Boller observes, "To be able to go from the very start, from the very first image, to the present and move forward provides not only a sense of completeness, but also the potential for new discoveries."

Table 2: Interactively explore your world your way with nearly 20 years of MODIS global imagery and the EOSDIS Worldview data visualization application

• On May 28, 2018, a series of potent dust storms swept across Iran, Turkmenistan, Afghanistan, and Pakistan. Accuweather reported winds approaching hurricane-force of 110 km/hr—near the city of Zabol in eastern Iran. Visibility dropped to zero at several points during the storms that lasted up to 12 hours in some places. News media claimed that as many as 100 people were injured across the region. 53)

- Meteorologists noted that the late-May dust storms were “caused by a strong upper level storm system that tracked north of the region, bringing thunderstorms to Turkmenistan and northern Afghanistan, but just producing powerful winds in eastern Iran.” SST (Sea Surface Temperatures) in the Arabian Sea have been about 1.5 to 2º C above normal in May, which could be contributing to the development of potent winds and storm fronts blowing across the Middle East and India this spring.

- Iran is mostly arid or semiarid, with deserts making up at least 25 million hectares (250,000 km2) of the country’s area. That already dry landscape has been parched by drought over the past year. Iranian environmental officials recently reported that 18 wetlands have completely dried up in recent months, and another 24 are in critical condition. Lake Urmia has been affected by warmer weather and drier than normal conditions over the past few decades. Such conditions have increased the amount of sand and dust available to be picked up by strong winds.

- Several governments and international groups have been looking for solutions to ease the region’s water and dust problems, which are partly due to drought and global warming, but also attributed by some scientists to uneven water management practices (irrigation, storage, treatment, and groundwater pumping). In the meantime, the Iranian government recently reported that it would be spreading petroleum-based mulch across 46,000 hectares of the desert this year in order to cut down on dust pollution.

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Figure 67: MODIS on NASA's Terra satellite acquired this image of the dust storms on May 28, 2018. Such storms, sometimes known as haboobs, are dramatic events associated with weather fronts, and they often appear as walls of sand and dust marching across the landscape. Like thunderstorms, haboobs tend to abrupt and short-lived (image credit: NASA Earth Observatory, image by Joshua Stevens, using MODIS data from LANCE/EOSDIS Rapid Response, story by Mike Carlowicz)

• On May 3, 2018, a new eruption began at a fissure of the Kilauea volcano on the Island of Hawaii. Kilauea is the most active volcano in the world, having erupted almost continuously since 1983. Advancing lava and dangerous sulfur dioxide gas have forced thousands of residents in the neighborhood of Leilani Estates to evacuate. A number of homes have been destroyed, and no one can say how soon the eruption will abate and evacuees can return home. 54)

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Figure 68: On May 6, 2018, at approximately 11 a.m. local time, the MISR (Multi-angle Imaging SpectroRadiometer) instrument on the Terra satellite captured this view of the island as it passed overhead. Much of the island was shrouded by clouds, including the fissure on its eastern point. However, an eruption plume is visible streaming southwest over the ocean. The MISR instrument is unique in that it has nine cameras that view Earth at different angles: one pointing downward, four at various angles in the forward direction, and four in the backward direction. This image shows the view from one of MISR's forward-pointing cameras (60º), which shows the plume more distinctly than the near-vertical views (image credit: NASA)

- The information from the images acquired at different view angles is used to calculate the height of the plume, results of which are superimposed on the right-hand image. The top of the plume near the fissure is at about 2,000 m altitude, and the height of the plume decreases as it travels south and west. These relatively low altitudes mean that the ash and sulfur dioxide remained near the ground, which can cause health issues for people on the island downwind of the eruption. The "Ocean View" air quality monitor operated by the Clean Air Branch of the State of Hawaii Department of Health recorded a concentration of 18 µg/m3 of airborne particles less than 2.5 µm in diameter at 11 a.m. local time. This amount corresponds to an air quality rating of "moderate" and supports the MISR results indicating that ash was most likely present at ground level on this side of the island.

- These data were acquired during Terra orbit 97780. The smoke plume height calculation was performed using the MISR MINX (INteractive eXplorer) software tool, which is publicly available at https://github.com/nasa/MINX. The MISR Plume Height Project maintains a database of global smoke plume heights, accessible at https://www-misr.jpl.nasa.gov/getData/accessData/MisrMinxPlumes2/.

• May 07, 2018: Loktak Lake is not only the largest freshwater lake in northeast India, it is also home to unique floating islands called “phumdis.“ These circular landmasses are made of vegetation, soil, and organic matter (at different stages of decomposition) that has been thickened into a solid form. The islands have a spongy surface that feels like a trampoline. Like an iceberg, most of the mass of phumdis lies below the water surface. During the dry season, when water levels drop, the living roots of the islands can reach the lakebed and absorb nutrients. 55)

- Speckled across this Loktak Lake, the several thousand phumdis and its surrounding waters are vital for irrigation, drinking water, food supplies, thus the lake has been referred as the “lifeline of Manipur“ state. Thousands of fishermen make their livelihood in the waters, catching about 1,500 tons of fish every year. Children and illiterate adults also attend a school located on one of the floating islands.

- The phumdis support around 200 species of aquatic plants and 400 species of animals, including the rare Indian python. The largest island is home to the Keibul Lamjao, the world’s only floating national park. It serves as a habitat for the endangered brow-antlered sangai, or "dancing deer," whose hooves have adapted to the island’s spongy ground. The park, covering 40 km2, was specifically created to preserve the deer, which were once thought to be extinct. The habitat is composed of floating meadows and a raised strip of hard ground that separates the park into northern and southern zones.

- The construction of the Ithai Dam in the 1980s — built to provide power for India’s northeast states — has threatened the life of the islands. The dam south of Loktak Lake has caused water levels to remain high year-round, preventing the phumdis from sinking and reaching the lakebed for nutrients. As a result, the phumdis are slowly thinning and breaking apart.

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Figure 69: The satellite images of Loktak Lake (Figures 69 and 70) were acquired on March 19, 2018, by ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) on the Terra satellite (image credit: NASA Earth Observatory, images by Joshua Stevens, using data from NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team, story by Kasha Patel)

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Figure 70: Overview image of Loktak Lake in India (image creedit: NASA Earth Observatory)

• April 28, 2018: Following a late-spring snowstorm in the Upper Midwest, rapidly melting snow filled rivers and streams and sent suspended sediment swirling in shallow parts of the Great Lakes. 56)

- Sediment loads tend to be especially heavy in the western end of Lake Erie. Of all the Great Lakes, Erie usually has the most sediment loading because of extensive farmland and cities near its shores. Since it is also the shallowest of the lakes, winds and currents can easily stir up sediments (quartz sand and silt, as well as calcium carbonate from limestone) on the lake bottom. And farmland, particularly fields that lack winter cover crops, tends to give up large amounts of sediment to rivers and streams.

- The situation is similar around Saginaw Bay, part of Lake Huron. More than half of the land surrounding the bay is used for agriculture, so spring runoff generally carries very large amounts of sediment.

- Landsat-8 and Sentinel-2 recently captured higher-resolution images of sediment in Saginaw Bay as well.

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Figure 71: MODIS on NASA's Terra satellite captured this image on April 20, 2018. After the storm, bloated rivers and streams dumped sediment-rich water into the lakes. Brisk spring winds combined with lake currents to send tendrils of mud and other debris swirling into deeper, bluer waters (image credit: NASA Earth Observatory, image by Adam Voiland, using MODIS data from LANCE/EOSDIS Rapid Response, story by Adam Voiland)

• April 17, 2018: Crops have withered and ranchers are culling herds after an unusually dry growing season in a country that is among the world’s top producers of soybeans and corn. Argentina’s soy production is projected to decline 31 percent and corn by 20 percent in 2017–2018 compared to the prior growing season, according to the U.S. Foreign Agricultural Service. 57)

- The economic consequences of the drought have been significant. Since December 2017, corn prices in the U.S. have risen 14 percent, and soybean prices are up 8 percent. Losses in Argentina are expected to surpass $3.4 billion, making the drought the most expensive natural disaster in 2018 so far.

- MODIS is just one of several satellite instruments useful for monitoring drought (Figure 72). The soil moisture maps (Figure 73) were produced with data collected on April 3, 2017, (left) and April 6, 2018, (right) by NASA’s SMAP (Soil Moisture Active Passive) satellite. SMAP carries a radiometer that measures soil moisture in the top 5 cm of the ground. Dark green and blue areas are progressively wetter.

- Despite the projected declines in Argentina’s soy crop, an unusually big crop in Brazil should help keep the global supply of soy at very high levels.

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Figure 72: The MODIS instrument on NASA's Terra satellite captured these natural-color images of the flat, fertile Pampas region of central Argentina. The Pampas appeared lush and green in April 2017 (left) in contrast to the browner landscapes (right) visible one year later (image credit: NASA Earth Observatory, images by Joshua Stevens, using MODIS data from LANCE/EOSDIS Rapid Response. Story by Adam Voiland)

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Figure 73: Soil moisture map comparison of Argentina acquired with SMAP on April 3, 2017 (left) and on April 6, 2018 (right), image credit: NASA Earth Observatory, images by Joshua Stevens, using soil moisture data courtesy of JPL and the SMAP Science Team

• March 29, 2018: Days of heavy rains drenched several watersheds in central and northern Queensland in early March 2018. Following the deluge, NASA satellites collected images of the pulse of water as it flowed south through braided rivers in Australia’s Channel Country, a desert region known for becoming lush with greenery after floods. 58)

- The MODIS instrument on NASA’s Terra and Aqua satellites captured this sequence of six images between March 11 and March 26, 2018. It shows the progress of water (light blue) on the Hamilton, Diamantina, and Thomson Rivers. The images use a combination of infrared and visible light to increase the contrast between water and land.

Figure 74: MODIS on Terra and Aqua acquired this sequence of images between 11-26 March 2018 (image credit: NASA Earth Observatory, images by Joshua Stevens, using MODIS data from LANCE/EOSDIS Rapid Response. Story by Adam Voiland)

- These three rivers drain from far to the north into basins near the border with South Australia, where water spreads out in large, shallow lakes. The rivers flow south toward the lowest point in Australia—Lake Eyre—partly because coastal mountain ranges block routes to the sea. As of March 27, 2018, flood water on the Diamantina had flowed as far south as Betoota and had begun to trickle into Birdsville, a remote town on the edge of the Simpson Desert.

- Northern Queensland is still being hammered by heavy rain. As the remnants of a tropical cyclone passed over the region on March 27, some areas received up to 400 mm of rain, according to Australia’s Bureau of Meteorology.