Minimize Sentinel-2 highlights from 2016 to 2015

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Mission status and imagery in the period of 2016 to 2015


• December 23, 2016: Sentinel-2A takes us over northwestern China near the border with Kazakhstan and Kyrgyzstan in this false-color image. The mountains pictured are part of the Tian Shan range, which stretches about 2800 km across this border region, making it one of the longest mountain ranges in Central Asia. 1)

- The glaciers of Tian Shan have lost about a quarter of their ice mass since the 1960s, and scientists estimate that half of the remaining glaciers will have melted by 2050. Glaciers are a key indicator of climate change, and their melting poses threats to communities living downstream.

- We know well that snow and clouds are both white – had this image (Figure 1) been in true color, we wouldn't be able to differentiate between the two. But Sentinel-2's imager can view the area in different parts of the spectrum, and can separate clouds from snow. In this image, clouds are white while snow appears blue. This is particularly important for mapping snow cover. A few clouds can been seen over the mountains near the center of the image, with thicker cloud cover in the valleys to the north.

- The orange area on the right side of the image is part of the Bayanbulak Basin, a large grassland area of about 24 000 km2. Although not pictured, the basin also hosts an important wetland and China's very own ‘Swan lake' – the highest-altitude breeding ground for swans in the world.

- This area of the Tian Shan mountains in China's Xinjiang Region became a UNESCO World Heritage Site in 2013.

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Figure 1: This image of China's Tian Shan range, observed by the Sentinel-2A satellite, was captured on 18 November 2016 (image credit: ESA, the image contains modified Copernicus Sentinel data (2016), processed by ESA)

• December 20, 2016: Images from the Sentinel-2A satellite from February to October 2016 (Figure 2) show the changing landscape in Spain's Brazo de Este natural park and around the city of Los Palacios y Villafranca. 2)

- The Copernicus Sentinel-2 mission is designed to provide images that can be used to distinguish between different crop types as well as data on numerous plant features, such as leaf area, chlorophyll content and water content – all essential for accurately monitoring plant growth.

Figure 2: Part of the Guadalquivir river basin, the area pictured has a rich agriculture with crops including rice, watermelon, pepper, cucumber, tomato and quinoa. In this animation we can clearly see changes in the fields as different crops grow at different rates, and are harvested in different seasons (image credit: ESA, the image contains modified Copernicus Sentinel data (2016), processed by ESA)

• December 16, 2016: Seville, the capital of the Andalusian autonomous community and the province of Seville, Spain, is located on the Guadalquivir river (Figure 3). While the original course of the river is visible snaking through the city on the right, we can see where water has also been redirected in a straighter course on the left. 3)

- The fertile valley of the Guadalquivir is evident by the plethora of agricultural structures, particularly noticeable in the upper right. The Sierra Morena mountain range runs north of the Guadalquivir basin, and we can see the foothills in the upper-left corner.

- Another notable feature in the upper-central section of the image is the open pit copper mine, appearing white. This type of mining is often practised when deposits of minerals or rocks are found near the surface. To the west of this mine, two other open-pit mines are filled with water.

- South of these water-filled mines we see two circular structures reminiscent of clamshells. These are large solar power plants, where mirrored panels are positioned to face a solar power tower –sitting at the southernmost tip of the structures seen here – which receives the focused sunlight and acts as a furnace to produce energy.

- Seville has a municipal population of about 703,000 as of 2011, and a metropolitan population of about 1.5 million, making it the fourth-largest city in Spain. Its Old Town, with an area of 4 km2, contains three UNESCO World Heritage Sites: the Alcázar palace complex, the Cathedral and the General Archive of the Indies.

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Figure 3: The western area of Spain's Province of Seville and its capital with the same name (right) is pictured in this image from the Sentinel-2A satellite. The image was acquired by the Sentinel-2A satellite on 26 July 2016 (image credit: ESA, the image contains modified Copernicus Sentinel data (2016), processed by ESA)

• December 2, 2016: Multiple scans from the Copernicus Sentinel-2A satellite have been stitched together to create this complete image of Switzerland (Figure 4). 4)

- The southern part of the country is dominated by the Alps, some of which are snow-capped. One of the more obvious features in the lower central part of the image is the curved x-shape of the Aletsch Glacier, the largest in the Alps. Owing to climate change, the glaciers in this region are showing long-term retreat.

- North of the Alps, the landscape descends into the Central Plateau, which covers about a third of Switzerland and is home to major cities like Zurich and the de facto capital city, Bern. It is the most densely populated region and hosts the majority of the country's industry, manufacturing and farming.

- Along the northwestern edge of the country are the Jura mountains, consisting of a sequence of ‘folds' in the geology, visible in the image as linear ridges running roughly southwest to northeast.

- Switzerland has thousands of lakes shaped by glaciers during the last ice age, about 15,000 years ago. Lake Geneva in the west is shared with France, while Lake Constance in the east is shared with Germany and Austria, making Lake Neuchâtel in the northwest the largest entirely within Switzerland. The lakes appear in different colors owing to variations in algae content or to the presence of finely ground rock flowing in from the mountain glaciers.

- Near the center of the country we can see Lake Lucerne with its four ‘arms'. The city of Lucerne sits on the western end of the lake, and is the site of the latest ESA ministerial council.

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Figure 4: Sentinel-2A image of Switzerland at 10 m resolution (image credit: ESA, the image contains modified Copernicus Sentinel data (2016), processed by GeoVille)

• November 25, 2016: A detailed land-cover map showing forest in Chiapas state in southern Mexico. The map (Figure 5) was produced using Copernicus Sentinel-2 optical data from 14 April 2016. It shows the kind of products that are possible through the new ESA-backed Forestry Thematic Exploitation Platform (F-TEP). Such products can support initiatives such as the UN's Reduced Emissions from Deforestation and Degradation (REDD+), which is a global agreement that developing countries should receive financial compensations for slowing the rates of deforestation and forest degradation in recognition of the role of forests as carbon sinks. 5)

- "F-TEP is a new ‘one-stop shop' online platform enabling the forestry sector to make easier use of satellite data," explains Tuomas Häme of VTT Technical Research Center of Finland, managing the development of the platform for ESA. "Users are able to map and explore their forests from the comfort of a web-based browser, within which they can rapidly access and process all available data, then disseminate the results."

- As part of a pilot project, the platform is being used to map the extensive Chiapas forest to assess its carbon stocks, with the Ministry of Environment and Natural History of the state government of Chiapas and several Mexican non-governmental organizations. Chiapas is the second most forested state in Mexico, and home to the Lacandon jungle – one of the last major tropical rainforests in the northern hemisphere. Covering 600,000 hectares, it is home to about 60% of Mexico's tropical tree species, 3500 species of plants and more than 1600 species of animals.

- The mapping is performed through an automated process with full 10 m-resolution Sentinel-2 images being run through ‘decision tree' software to pick out trees. Very high-resolution 1 m-class satellite imagery is used to cross-check the results, combined with cross-checks from the ground.

- Achieving a standardized space-based method of assessing forest carbon stocks could be key to implementing the REDD+ scheme. — While comparable forest mapping once took about three years to produce, use of the platform combined with Sentinel-2's frequent coverage allows new maps to be updated in a matter of weeks.

Figure 5: The Chiapas forest land-cover map (image credit: ESA, the image contains modified Copernicus Sentinel data (2016), processed by VTT Technical Research Center of Finland Ltd.)

• October 2016: The Multi-Spectral Instrument Performance 6)

The first months of the in-orbit operations, have been the opportunity to successfully complete the commissioning of satellite and to get first trends in routine phase of the instrument Beginning of Life performance. Radiometric and geometric performance have been evaluated, showing a very good compliance to the key mission requirements (Table 1). On radiometric side, the SNR for the RGB bands (10m bands) is close to 40% with the smallest margin >20% for B8. For the IR bands, the noise is kept low allowing to have margin on Signal-to-Noise ratio above 50%. Radiometric accuracy evaluated by comparison of in-situ or vicarious site allow to consider an accuracy better or equal to 5% for the VNIR bands. The achieved MTF (Modulation Transfer Function) is above 0.15 for all 10 m and 20 m VNIR bands, in both along- and across-track directions. For SWIR bands, the MTF is well achieved in the along-track direction, with a marginal compliance in the across-track for one of the 2 bands.

On the geometric side, the geo-location accuracy is better than 12.5 m at 2σ, reaching already the requirement expected with GCP (Ground Control Point). The band-to-band coregistration is better than 0.3 pixel at 2σ is met with a comfortable margin and is expected to be further improved (<10 m) by a refinement of the on-ground post-processing and usage of the new Global Reference Image.

Type

Subject

Performance estimation

Compliance

Radiometric
performance

SNR (Signal-to-Noise Ratio) and minimum, reference and maximum radiance levels for each spectral band.

All bands compliant with
> 20% margin

Yes

Radiometric
performance

The absolute radiometric accuracy shall be 3% (goal) / 5% (threshold).

B1 to B9: < 5%±2%

Yes

Optical
performance

The inter-channel spatial co-registration of any two spectral bands shall be better than 0.30 of the coarser achieved spatial sampling distance of these two bands

< 0.26 pixel at 3σ

Yes

Optical
performance

The system modulation transfer function (MTF), at Nyquist frequency, shall be higher than 0.15 and lower than 0.30, in both across-track and along-track, for the spectral bands at 10 and 20 m SSD, and not higher than 0.45 for the spectral channels at 60 m SSD. MTF curves over the entire frequency range shall be calculated.

MTF > 0.15 for all bands
except for B11(0.147 in ACT)

Yes

Geometric
performance

The geo-location uncertainty shall be better than 20 m at 2σ confidence level (without Ground Control Points).

< 12.36 m at 2s

Yes

Table 1: Key mission performance of the Multi-Spectral Instrument

• November 18, 2015: Figure 6 of Sentinel-2A shows the Gibson Desert in western Australia. Covering an area of over 150,000 km2, the desert sports gravel terrains covered by desert grasses, as well as red sandy plains and dunefields. A drought in the 1980s forced the indigenous Pintupi people to the central-eastern area of the desert, where they made contact with Australian society in what is believed to be one of the last first-contact events in Australia. 7)

- On the left side of this false-color image, we see many strange shapes in varying shades of blue. These are the remnants of areas purposefully burned by the Pintupi people to encourage plant growth or drive game animals into the open. — Many of the Pintupi people moved to settlements when the British military began testing missiles in the region in the 1950s. The areas that they had burned became overgrown, becoming even more susceptible to manmade or lightning-caused fires, which then burn out of control, leaving behind large burned scars.

- In the lower-right corner of the image we can make out a circular structure. This is the Connolly Basin impact crater, believed to have been formed around 60 million years ago. Some 9 km across, the rim rises 25–30 m above the crater's basin.

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Figure 6: Sentinel-2A false color image of the Gibson Desert in Western Australia, captured on Dec. 25, 2015 (image credit: ESA, the image contains modified Copernicus Sentinel data (2015), processed by ESA)

• November 17, 2016: The image of Figure 7 shows the Frankfurt airport at upper center, the city itself, to the north-east of the airport, and the meeting of the Rhine and Main rivers, with the Rhine flowing from bottom center towards the upper left, and the much narrower Main flowing from top right through the city.

- It also shows the city of Darmstadt, 35 km south of Frankfurt, sitting on a gentle slope between the forested Odenwald mountains and the Rhine River. — Darmstadt is seen as the built-up area to the right of the ‘V' intersection between Autobahns 5 and 67, directly south of the airport. Darmstadt is an important center for scientific institutes, universities and high-tech companies – and, since 1967, it has hosted the center known today as ESA's European Space Operations Center (ESOC). It is home to Sentinel-1 and -2 mission control, from where the three satellites of the two dual missions are operated, 24 hours/day, year round. The fourth, Sentinel-2B, is set for launch in 2017.8)

- There are about 900 ESA staff and contractors working at the center, with 11 missions comprising 17 spacecraft now flying and nine missions in preparation. — In September 2017, the center will mark its 50th anniversary.

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Figure 7: This image spotlights the Rhine-Main area south of the city of Frankfurt, one of Europe's leading business, transport and innovation hubs. The image was acquired by the Sentinel-2A satellite on 29 August 2015 (image credit: ESA, the image contains modified Copernicus Sentinel data (2015), processed by ESA)

• October 28, 2016: Sentinel-2A brings us over the snowy landscape of the Putorana Plateau in northern Central Siberia (Figure 8). The area pictured shows part of the Putoransky State Nature Reserve, which is listed as a UNESCO World Heritage Site. Situated about 100 km north of the Arctic Circle, the site serves as a major reindeer migration route – an increasingly rare natural phenomenon – and is one of the very few centers of plant species richness in the Arctic. 9)

- Virtually untouched by human influence, this isolated mountain range includes pristine forests and cold-water lake and river systems. The lakes are characterized by elongated, fjord-like shapes, such as Lake Ayan in the upper-central part of the image. Zooming in on the lake we can see that it is mostly ice-covered, with small patches of water peeking through around its lower reaches.

- Another feature of this area are the flat-topped mountains, formed by a geological process called ‘plume volcanism': a large body of magma seeped through Earth's surface and formed a blanket of basalt kilometers thick. Over time, cracks in the rock filled with water and eroded into the rivers and lakes we see today.

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Figure 8: This Sentinel-2A image of the Putorana Plateau in Siberia was acquired on March 2, 2016 (image credit: ESA, the image contains modified Copernicus Sentinel data (2016), processed by ESA)

• October 21, 2016: Part of Nepal, including its capital city, Kathmandu, and the Himalayan foothills are pictured in this satellite image (Figure 9). Vegetation appears red in this false-color image, while waterways and buildings appear light green and blue. 10)

- Surrounded by four mountain ranges, Kathmandu valley at the top of the image is recognized as a UNESCO World Heritage Site for its temples and monuments. However, some of these sites collapsed during the April 2015 earthquake that struck the region, claiming thousands of lives and causing widespread damage throughout the valley.

- This image demonstrates just a slice of Nepal's varied terrain: from the mountains to the north to the plains in the south. We can see how water runs off of the mountains, forming large rivers that cut through the forested plain, with some areas of agriculture. The lower part of the image appears hazier than the mountainous areas because humidity is higher in the plains.

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Figure 9: Sentinel-2A image of Kathmandu, Nepal's capital city, and its surroundings (image credit: ESA, the image contains modified Copernicus Sentinel data (2015), processed by ESA)

• Sept. 30, 2016: Part of the Anti-Atlas mountains, bordering the Sahara Desert in northwestern Algeria, is pictured in this satellite image of Sentinel-2A (Figure 10). 11)

- The Anti-Atlas range was born from continental collision, and geologists believe it was once higher than the Himalayas, but was reduced through erosion. Here the land is mostly dry and barren as the mountains belong to the Saharan climate zone. But some stream channels created by occasional water runoff or from when the climate was much wetter than today, are visible.

- The circle at the center of the image (Figure 10) is the Ouarkziz crater. Some 3.5 km in diameter, the crater was created when a meteor hit Earth less than 70 million years ago, when dinosaurs still roamed the planet.

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Figure 10: This image of the Ouarkziz crater (center of image) was captured by the Copernicus Sentinel-2A satellite on 9 March, 2016 (image credit: ESA, the image contains modified Copernicus Sentinel data (2016), processed by ESA)

• Sept. 14, 2016: The Figures 11 and 12 from Sentinel-2A show the beautiful lush Portuguese main island of Madeira before it was devastated by wildfires in August 2016. Madeira is famous for its rugged green landscape and is home to unique endemic flora and fauna. In fact, two thirds of the island is given over to national park to protect this natural environment. These ‘false-color' images (Figure 11 and 12) show the vegetation in red. By contrast, the image from 17 August shows large black patches where the fires encroached on the capital Funchal in the southeast and also further to the west, leaving the land scarred. 12)

- The recent devastation brought by wildfires to the beautiful Portuguese island of Madeira is all too clear in these images from Sentinel-2A.

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Figure 11: Sentinel-2A MSI image of Madeira acquired on 7 August 2016 (image credit: ESA)

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Figure 12: Sentinel-2A MSI image of Madeira acquired on 17 August 2016 (image credit: ESA)

• September 9, 2016: Plankton, the most abundant type of life found in the ocean, are microscopic marine plants that drift on or near the surface of the sea (Figure 13). They are sometimes referred to as ‘the grass of the sea' because they are the basic food on which all other marine life depends. Since plankton contain photosynthetic chlorophyll pigments, these simple organisms play a similar role to terrestrial ‘green' plants in the photosynthetic process. Plankton are able to convert inorganic compounds such as water, nitrogen and carbon into complex organic materials. 13) 14)

- With their ability to ‘digest' these compounds, they are credited with removing as much carbon dioxide from the atmosphere as their counterparts on land. As a result, the oceans have a profound influence on climate. Since plankton are a major influence on the amount of carbon in the atmosphere and are sensitive to environmental changes, it is important to monitor and model them into calculations of future climate change.

- Although some types of plankton are individually microscopic, the chlorophyll they use for photosynthesis collectively tints the color of the surrounding ocean waters, providing a means of detecting these tiny organisms from space with dedicated sensors, such as Sentinel-2's MSI (Multispectral Imager) with 13 spectral bands.

- Some algae species are toxic or harmful. If they surge out of control during optimal blooming conditions they can exhaust the water of oxygen and suffocate larger fish. This phenomenon has dramatically increased in recent decades, and is particularly dangerous to fish farms because the fish cannot flee affected areas. Early warning of harmful blooms from satellites can help to prevent fish farmers from losing their stock, as it happened in Chile recently.

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Figure 13: Although it may appear as a watercolor painting, this image is a natural-color capture of a plankton bloom in the Barents Sea by the Sentinel-2A satellite, acquired on June 30, 2016 (image credit: ESA, contains modified Copernicus Sentinel data (2016), processed by ESA)

• September 7, 2016: On July 17, 2016, a huge stream of ice and rock tumbled down a narrow valley in the Aru Range of Tibet. When the ice stopped moving, it had spread a pile of debris that was up to 30 meters thick across 10 km2. Nine people, 350 sheep, and 110 yaks in the remote village of Dungru were killed during the avalanche (Figure 14). 15) 16)

- The massive debris field makes this one of the largest ice avalanches ever recorded. The only event of a comparable size was a 2002 avalanche from Kolka Glacier in the Caucasus region, explained Andreas Kääb, a glaciologist at the University of Oslo. The cause of the avalanche is unclear. "This is new territory scientifically," said Kääb. "It is unknown why an entire glacier tongue would shear off like this. We would not have thought this was even possible before Kolka happened."

- The OLI (Operational Land Imager) instrument, a similar instrument on Landsat-8, acquired an image on June 24, 2016 (Figure 15), that shows the same area before the avalanche.

- Kääb's preliminary analysis of satellite imagery indicates that the glacier showed signs of change weeks before the avalanche happened. Normally, such signs would be clues the glacier might be in the process of surging, but surging glaciers typically flow at a fairly slow rate rather than collapsing violently in an avalanche.

- After inspecting the satellite imagery, University of Arizona glaciologist Jeffrey Kargel agreed that a surging glacier could not be the cause. "The form is completely wrong," he said. "It must be a high-energy mass flow. Maybe liquid water lubrication at the base played some role," he said.

- Tian Lide, a glaciologist at the Chinese Academy of Sciences, visited the site in August and described the avalanche as "baffling" because the area where the ice collapse began is rather flat. "We failed to reach the upper part of the glacier for safety reasons," he said in an email, "but we will go the upper part [later] to see if we can find some more hints about what caused the glacier disaster."

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Figure 14: The MSI (Multispectral Imager) on the Sentinel-2A captured this image of the debris field on July 21, 2016 (image credit: ESA, NASA Earth Observatory)

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Figure 15: OLI image of Landsat-8 acquired on June 24, 2016 (image credit: NASA Earth Observatory, images by Joshua Stevens, using Landsat data from the USGS)

• September 2, 2016: The Upsala Glacier in Argentina's Los Glaciares National Park is pictured in this Sentinel-2A image (Figure 16). The park was named a UNESCO World Heritage site in 1981 and is the largest in the country, covering an area of over 7000 km2. 17)

- Many glaciers in the national park and in the wider Patagonian Ice Field have been retreating during the last 50 years because of rising temperatures. The Upsala Glacier has retreated more than 3 km in the past 15 years.

- Glaciers are the largest reservoirs of freshwater on our planet, and their melting or growing is one of the best indicators of climate change. Satellite data can help to monitor changes in glacier mass and, subsequently, their contribution to rising sea levels.

- Taking a closer look at the terminus of the Upsala Glacier, we can see how icebergs have broken off and are floating in the water of the upper reaches of Lake Argentino. The lake's unique color is attributed to ‘glacier milk' – suspended fine sediment produced by the abrasion of glaciers rubbing against rock. The darker lines following the flow of the glacier are moraines: accumulations of rock, soil and other debris – including glacial milk – that have been deposited by the glacier.

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Figure 16: The Upsala Glacier in Argentina's Los Glaciares National Park is pictured in this Sentinel-2A image from 22 January 2016 (image credit: ESA, contains modified Copernicus Sentinel data (2016), processed by ESA)

 

• May 27, 2016: The Sentinel-2A satellite takes us to the diverse landscape of the eastern Atacama desert in South America. The region pictured (Figure 17) lies around 200 km east of the Chilean city of Antofagasta on the Pacific coast (not pictured), and is virtually devoid of vegetation. 18)

- At the top of the image we can see part of Chile's largest salt flat, the Salar de Atacama. With an average elevation of some 2300 m above sea level, it is formed by waters flowing down from the Andes, which, having no drainage outlets, are forced to evaporate, leaving salt deposits.

- It is the world's largest and purest active source of lithium, containing some 30% of the world's lithium reserve base, and providing almost 30% of the world's lithium carbonate supply.

- The bright turquoise rectangles and squares visible along the top part of the image are evaporation ponds. Subsurface salt brines are pumped from beneath the saline crust in two different areas. In one of them, extracted salt brines have unrivalled concentration levels of potassium and lithium. In the other, the brines obtained contain high concentrations of sulphate and boron.

- In the lower right part of the image we can see the Socompa stratovolcano, known for its ‘debris avalanche deposit' where the land collapsed on its western rim some 7000 years ago. The area has since been partially filled by lava, and we can see dark lava flows around the volcano.

- The MSI (Multispectral Instrument) on Sentinel-2 uses parts of the infrared spectrum to analyze mineral composition where vegetation is sporadic. In this false-color image, the intense shades of brown and orange come from the use of an infrared part of the spectrum leading to an exaggeration of color intensity.

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Figure 17: This Sentinel-2A image of Chile's salt flat was acquired on March 8, 2016 (image credit: ESA, the image contains modified Copernicus Sentinel data [2016], processed by ESA)

• May 20, 2016: Rolling sand dunes in the expansive Rub' al Khali desert on the southern Arabian Peninsula are pictured in this image from the Sentinel-2A satellite (Figure 18). Also known at the ‘Empty Quarter', the Rub' al Khali is the largest contiguous sand desert in the world. Precipitation rarely exceeds 35 mm a year and regular high temperatures are around 50°C. 19)

- The yellow lines and dots in this false-color image are sand dunes. Looking closer at the dunes in the lower right, many have three or more ‘arms' shaped by changing wind directions and are known as ‘star dunes'. They tend to ‘grow' upwards rather than laterally, and reach up to 250 m in height in some parts of the Rub' al Khali.

- The dunes are interspersed with hardened flat plains – remnants of shallow lakes that existed thousands of years ago, formed by monsoon-like rains and runoff. The multispectral instrument on Sentinel-2 uses parts of the infrared spectrum to detect subtle changes in vegetation cover, but can also see changes in mineral composition where vegetation is sparse. In this image, shades of brown to bright purple show the mineral composition, possibly including salt or gypsum.

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Figure 18: This image was captured by Sentinel-2A on 22 December 2015 (image credit: ESA, the image contains modified Copernicus Sentinel data [2016], processed by ESA)

• May 19, 2016: Sentinel-2A is demonstrating how it can be used to help forecast ocean waves around our coasts: sunlight reflected from the water surface reveals complex waves as they encounter the coastline and seafloor off the tip of Dorre Island, Western Australia (Figure 19). 20)

- ESA's ocean scientist, Craig Donlon, explained, "The instrument images the same ocean scene from slightly different angles and at slightly different times. -Scientists at OceanDataLab processed the data to determine the distribution of ocean waves and the direction they are heading. This is extremely important for anyone working at sea."

- The fine resolution of Sentinel-2A's multispectral imager provides a view of the tilting facets of the waves, expressed as measurable intensity contrasts. The instrument images the same ocean scene from slightly different angles and at slightly different times. Scientists at OceanDataLab first transformed these radiances into estimates of sea-surface slope and then ran a cross-spectral analysis to determine the wave spectrum and wave velocity.

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Figure 19: This image was taken by the Copernicus Sentinel-2 satellite on 1 October 2015. It shows how reflection of solar radiation by the sea surface reveals the complex patterns of waves as they interact with the coastline and seafloor off the tip Dorre Island, Western Australia. Several superimposed wave sets that have been reflected and bent by the coastal features and the shape of the seabed can be seen. Longer swell waves are also evident, with surf and breaking waves at the coastline itself (image credit: ESA, the image contains modified Copernicus Sentinel data (2016), processed by OceanDataLab)

• May 18, 2016: Using almost 7000 images captured by the Sentinel-2A satellite, this mosaic of Figure 20 offers a cloud-free view of the African continent – about 20% of the total land area in the world. The majority of these separate images were taken between December 2015 and April 2016, totalling 32 TB of data. Thanks to Sentinel-2A's 290 km-wide swath and 10-day revisit at the equator, the chance of imaging Earth's surface when the skies are clear is relatively high. Nevertheless, being able to capture the Tropics cloud-free over the five months is remarkable. 21)

- Sentinel-2A's identical twin, Sentinel-2B, is due to be launched in 2017. As a constellation, the two satellites will orbit 180° apart. Along with their wide swaths, this will allow Earth's main land surfaces, large islands, as well as inland and coastal waters to be covered every five days. This will further improve the probability of gaining a cloud-free look at a particular location.

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Figure 20: This African mosaic, the first mosaic of Africa generated through ESA's Climate Change Initiative Land Cover project, was presented at the Living Planet Symposium in Prague, Czech Republic (image credit: this image contains modified Copernicus Sentinel data (2016), processed by Brockmann Consult/ Université catholique de Louvain, The Netherlands)

• May 9, 2016: Different types of crops growing east of the Czech capital, Prague (left), are distinguished in this land cover classification image (Figure 21). This image was produced in collaboration with the European Commission (lead by the Joint Research Centre), the State Agricultural Intervention Fund of the Czech Republic and ESA. 22)

- With its 13 spectral bands, the Sentinel-2 mission for Europe's Copernicus program is the first optical Earth observation mission of its kind to include three bands in the ‘red edge', which provide key information on vegetation state. Sentinel-2 is designed to provide images that can be used to distinguish between different crop types as well as data on numerous plant indices, such as leaf area, leaf chlorophyll and leaf water – all essential to monitor plant growth accurately.

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Figure 21: This crop map was created by combining over 1000 scenes from the Sentinel-1, Sentinel-2 and Landsat-8 satellites taken over the course of 2015 (image credit: DUE Sentinel-2 for Agriculture project; contains modified Copernicus Sentinel data (2015))

• April 29, 2016: Figure 22 of Sentinel-2A is an image of central western Namibia, an area surrounding the Namib Naukluft Park. The National Park includes part of the Namib – the world's oldest desert – and the Naukluft Mountain range. It is the largest game park in Africa and the fourth largest in the world. 23)

- A typical west coast desert, moisture enters as fog, from the Atlantic Ocean, rather than receiving actual rainfall. A phenomenon also found along the west coasts of South and North America, the surface water of Namibia's coast is relatively cold, so that moist air moving in with westerly winds cools and falls as rain before it reaches the coast, allowing only fog to reach inland.

- The fog enables life in this extremely arid region, for snakes, geckos and particular insects like the fogstand beetle, which survives by collecting water on its bumpy back from early-morning fogs, as well as hyenas, gemsboks and jackals.

- The winds carrying the fog also create the imposing sand dunes, whose age is rendered by the burnt orange color. The iron in the sand is oxidized, developing this rusty-metal color over time. It becomes brighter as the dune ages, as is clearly visible along the middle of this natural-color image.

- Also visible along the top-left part of the image is the Kuiseb River bordered on one side by some of the tallest sand dunes in the world, and on the other by barren rock. The river blocks the movement of the dunes, which are blown northwards by the winds.

- A road cuts through the top-right corner of the image. It is part of the C14 Highway, which runs for some 600 km from Walvis Bay, through Helmeringhausen and ends in Goageb.

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Figure 22: Sentinel-2A image of central western Namibia, an area surrounding the Namib Naukluft Park, acquired on January 28, 2016 (the image contains modified Copernicus Sentinel data [2016], processed by ESA)

March 31, 2016: ESA and Australia's national geological survey, Geoscience Australia, today agreed to cooperate to ensure data from the EU's Sentinel satellites are accessible in Southeast Asia and the South Pacific. The agreement supports the Australian government and European Commission's partnership to ensure the EU's Copernicus Earth observation program benefits their citizens and the broader international community. 24)

- A key component of the cooperation will be the establishment of a regional data access and analysis hub managed by GA (Geoscience Australia). This hub will greatly improve access to Copernicus data in a region which is densely populated and experiencing high rates of economic growth, but which faces significant challenges in areas where Earth observation can help. These challenges include the protection of environmental assets, promotion of sustainable natural resource development and risk reduction from natural disasters.

- ESA will supply GA with high-speed access to data from the Sentinel satellites through its Copernicus data access infrastructure. Through a consortium with Australia's CSIRO (Commonwealth Science and Industrial Research Organization), Canberra and Australian state governments, GA will make the data hub available to users in the Southeast Asia and the South Pacific region. The hub is projected to provide access to over 12 PB (Petabytes) of data by 2025, and is expected to go beyond simply providing users with the ability to download Copernicus data.

- "The regional data hub will also provide a high-performance environment in which all the data can be analyzed and applied at full scale to big regional challenges like the blue economy, sustainable livelihoods and climate change adaptation," said GA's head of Earth and Marine Observations, Dr Adam Lewis. "By enabling multiple user groups, from multiple countries, to come together and ‘work around' such a comprehensive set of data, we are helping to make sure the full potential of the EU's amazing program is realized and that regional partners can find regional solutions to regional challenges."

- The data access hub will be established at Australia's National Computational Infrastructure, the largest facility of its kind in the southern hemisphere, taking advantage of the Australian government's investments in science and research infrastructure to support the region. The cooperation will also make it easier for European and Australian experts to collaborate on the calibration and validation activities that are fundamental to ensuring that users have access to high-quality satellite data and value-added products they can trust.

- "Through GA, CSIRO and many other players, Australia has long made a valued contribution to our calibration and validation activities. Its technical expertise, world-class facilities and the diversity of geographies they have access to makes them a key player," said Pier Bargellini from ESA's Copernicus Space Component Mission Management and Ground Segment Division. "Through this arrangement, we expect to see this grow even further, with Australia making a particular contribution to ensuring Copernicus data satisfies local and regional requirements."

- Under the arrangement, GA will also act as a coordinating point for European partners to obtain access to Australian in-situ data, which is made available through the efforts of many Australian government agencies, research partnerships and universities.

- "The EU's Copernicus program is about applications and services, and these applications and services are most useful when satellite and in-situ data are integrated," said Andreas Veispak, the European Commission's Head of Unit for Space Data for Societal Challenges and Growth. "We welcome GA's commitment to act as a coordination point for access to in-situ data. Australia has a record of providing outstanding data, including through programs like the integrated marine observing system and terrestrial ecosystem research network. We are looking at linking Copernicus more closely to these efforts."

- The regional data hub will become operational on 1 July, 2016.

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Figure 23: Sentinel-2A captured Lake Amadeus in Australia's Northern Territory on 19 December 2015 (image credit: Copernicus Sentinel data (2015)/ESA) 25)

• March 25, 2016: The Etosha salt pan is the most prominent feature, forming part of the Kalahari Basin in northern Namibia (Figure 24). It is believed that a lake was first formed tens of millions of years ago. More recently – mere thousands of years ago – the Kunene River would have flowed through this area, filling the large lake before tectonic movement changed the river course. The lake then dried up, leaving behind some 4800 km2 of exposed minerals. 26)

- Today only the Ekuma River, seen flowing down from the upper left, feeds water into the pan – but very little water actually flows in as it seeps into the riverbed.

- Part of the wider Etosha National Park, the pan is a designated Ramsar wetland of international importance. It is the only known mass breeding ground for flamingos in Namibia, seeing as many as one million flamingos at a time during the wet season when rain water forms pools in parts of the pan.

- Built-up mounds of clay and salt throughout the pan also draw animals who use them as salt licks. Animals including lions, elephants, leopards and even black rhinoceroses can be seen in the park. The name ‘Etosha' means ‘great white place' in the language of the local Ovambo tribe – and looking at the image we understand why.

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Figure 24: This Sentinel-2A image of the Etosha salt pan in northern Namibia was acquired on September 18, 2015 (image credit: Copernicus Sentinel data (2016)/ESA)

March 15, 2016: ESA has agreed with NASA, NOAA and the USGS to make data available to them from the European Sentinel satellites. With the third Copernicus satellite, Sentinel-3A, recently launched, ESA has signed technical arrangements with these US agencies for accessing Sentinel data. These arrangements coordinate the technical implementation covering the Sentinel data access to the US. 27) 28)

- ESA and its international partners are pursuing Earth observation activities in a number of areas of common interest, and are sharing each other's satellite data. All sides are committed to the principle of full, free and open access to the European Sentinel and the NASA, NOAA and USGS Earth observation satellite data and information.

- The signed arrangement will allow NASA, NOAA and USGS to systematically retrieve the Sentinel data from a dedicated International Data Hub operated by ESA. These agencies will then transfer the data to the US, absorbing them in their existing data access systems, such as EarthExplorer and GloVIS, and disseminating them to their own user communities.

- For over three decades, ESA has been acquiring, processing and disseminating data from a number of US missions such as Landsat to the European user communities as part of its Earthnet Third Party Mission Program.

- While the US agencies' objective is to serve the US user communities with priority, the Sentinel data will continue to be freely accessible for Copernicus Services, as well as to users worldwide, through the ESA operated data hubs.

• Feb. 26, 2016: Like most of Egypt's landscapes, the image of Figure 25 is dominated by arid desert – namely the Eastern Desert between the Nile River and the Red Sea. The distinctive pattern of water erosion from rivers and streams is clearly visible as they make their way towards the Nile, at which point the rolling sandy highlands drop abruptly at the Nile valley, visible along the bottom of the image. 29)

- Fields of intensive farming along the Nile appear red owing to this false-color image being processed to include the near-infrared. The varying shades of red indicate how sensitive the MSI (Multispectral Instrument) on Sentinel-2 is to differences in chlorophyll content, providing key information on plant health.

- The Nile valley is one of the world's most densely populated areas. The river is the primary source of water for both Egypt and Sudan's populations, supporting life in an otherwise uninhabitable environment, as evidenced by the stark contrast between the colors of this image.

- Zooming in along the bottom of Figure 25, one can see clusters of black dots where cities and towns are located, in addition to the fields. In the lower right, just above the red area, there is an interesting pattern of roads from the bird's-eye view – possibly a developing residential area.

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Figure 25: Sentinel-2A image of central-eastern Egypt acquired on January 17, 2016 (image credit: Copernicus Sentinel data (2016)/ESA)

• Feb. 12, 2016: Figure 26 features the diverse landscapes of the autonomous Community of Madrid in the heart of Spain. The community and country's capital city is visible near the center of the image.30)

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Figure 26: Sentinel-2A acquired this image of Madrid and its surroundings on November 16, 2015 (image credit: Copernicus Sentinel data (2015)/ESA)

• January 26, 2016: ESA and Airbus DS signed a contract to deliver two further optical satellites for the European Copernicus program. As part of the Sentinel-2 Earth observation satellite system, these two new models, called "Sentinel-2C" and "Sentinel-2D", will observe the environment and land surfaces and continue from 2021 with the measurements carried out by the first two flight units as part of the European Copernicus program. As prime contractor, Airbus Defence and Space will lead an industrial consortium of more than 50 companies from 17 European countries and the USA. 31)

• January 22, 2016: The natural-color image of Sentinel-2A (Figure 27) features the small nation of Bahrain and parts of eastern Saudi Arabia. Located on the southwestern coast of the Persian Gulf, Bahrain is a small Arab state, made up of an archipelago consisting of Bahrain Island and some 30 smaller islands. The total area of Bahrain is about 780 km2. 32)

- In the middle of the image, on the Persian Gulf, the King Fahd Causeway is clearly visible. Built between 1981 and 1986, it consists of a series of bridges and stretches of road connecting Saudi Arabia and Bahrain. The Saudi and Bahraini passport control centers are also noticeable in the middle of the Causeway.

- On the right of the image is the island of Bahrain, home to some 1.5 million people, with its modern capital Manama featured at the top of the island. The greys represent the densely built city center and surrounding towns. Strikingly relaxed and cosmopolitan, Manama has been at the center of major trade routes since antiquity. On the top right part of the island, on a smaller island about 7 km northeast of the capital, Bahrain International Airport is visible.

- Most of Bahrain is a flat and arid desert plain, with recurrent droughts and dust storms the main natural dangers for its inhabitants. Famous for its pearl fisheries for centuries, today it is also known for its financial, commercial and communications sectors.

- Towards the central left part of the island, Bahrain University is observable. Also visible, the Al Areen Wildlife Reservation, both a nature reserve and zoo, one of the five protected areas of the country, and the only protected area on land.

- On the bottom-right tip of the island a series of horseshoe-shaped artificial atolls are clearly visible. Durrat Al Bahrain, one of the largest artificial islands in Bahrain, comprises six atolls and five fish-shaped islands.

- On the left side of the image, in Saudi Arabia, part of the Rub' al-Khali, the world's largest sand desert, is also visible.

- Distinct throughout the entire image, the striking variations of blue represent the shallow versus deep waters, with the presence of coral reefs.

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Figure 27: This Sentinel-2A image, acquired on Sept. 18, 2015, is showing the colors of the Persian Gulf and the archipelago of the island state of Bahrain (image credit: Copernicus Sentinel data (2015)/ESA)

 

Mission status and imagery of 2015

• December 18, 2015: The false-color image of Figure 28 features southern Mongolia, bordered by China to the south and Russia to the north. Known for its vast, harsh stretches of space and its nomadic people, Mongolia sits deep within eastern Asia, distant from any ocean. Home to the two-humped Bactrian camel, herds of horses and the Gobi Desert, Mongolia is predominantly a sandy and rocky plain, with an average elevation of some 1500 m above sea level. 33)

- The Gobi Desert covers parts of China and of southern Mongolia. It is a rain shadow desert, formed by the Himalayas blocking the Indian Ocean's rain from reaching the Gobi territory. Asia's largest desert and the fifth largest in the world, much of the Gobi is not sandy, but rocky. With long, cold winters and short, cool-to-hot summers, the climate of the Gobi Desert presents powerful extremes, with rapid temperature shifts of as much as 35ºC, not only seasonally but also within 24 hours. - At the bottom of the image, part of the Baga Bogd Mountain range is visible. Its highest peak has an elevation of 3600 m.

- Low vegetation is present during the warm months. This, along with some scattered trees, gives the red tones that can be seen in the image. Varying tones of red represent the various types of vegetation and the varying density and condition of the plants.

- The sharp image of the MSI (Multispectral Imager) on Sentinel-2A reveals spectacular erosion patterns where the eroded soil, with the help of rain, is carried from the mountain slopes to the lower regions.

- There is a very distinct body of water towards the top right part of the image, the Taatsiin Tsagaan Lake, one of the four saline lakes that make up the Valley of the Lakes. Mongolia joined the Ramsar Convention on 8 April 1998, which covers Wetlands of International Importance. The lake's depth and high concentration of salt give the water a vivid turquoise color.

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Figure 28: False-color image of southern Mongolia, acquired by Sentinal-2A on August 15, 2015 (image credit: Copernicus Sentinel data (2015)/ESA)

• December 11, 2015: The natural color image of Figure 29 features the area of Les Deux Alpes and surroundings, in France. A ski resort in the French Isère department, the village of Les Deux Alpes is located at an altitude of 1650 m with its ski lifts running up to 3600 m. Located near Western Europe's largest mountain, Mont Blanc, it accesses the greatest skiable glacier in Europe and is France's second oldest ski resort. 34)

- The relief differences in the area are clear thanks to Sentinel-2's high-resolution multispectral instrument. The brownish colors represent those parts of the mountains without vegetation or settlements. The village of Le Bourg-d'Oisans is clearly visible in the center of the image, with agricultural plots around it.

- The grey area on the top left corner is the city of Grenoble, in the Rhône-Alps region of southeastern France. It sits along the Isère River, at 214 m above sea level. Home to some 160 000 people, Grenoble's history goes back 2000 years. Today it is a leading scientific research center, renowned for research in nuclear physics and microelectronics.

- Among various bodies of water, the Lac Monteynard-Avignonet is clearly visible, snaking its way down the image. This is a 10 km-long and, in some places, 300 -wide artificial reservoir created in 1961. Often windy and rippled, the lake is considered to be one of the best places for wind and kite surfing in Europe.

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Figure 29: Sentinel-2A portrait of the Les Deux Alpes and surroundings in France, acquired on August 29, 2015 (image credit: Copernicus Sentinel data (2015)/ESA)

• December 3, 2015: ESA is pleased to announce the availability of Sentinel-2A orthorectified products in the Sentinel Data Hub. Any products acquired from 28 November onward are available to any user. Sentinel-2 products can be searched for by selecting Sentinel-2 in the search menu, or search bar. 35)

- Sentinel-2 is currently in its Ramp-up Phase, operating the following observation scenario: with an average of 10 minutes MSI sensing time per orbit, Sentinel-2A is acquiring Europe and Africa systematic on every orbit, while the rest of the sunlit world land masses between 56º South and 84º North will be mapped with a 30 day revisit time.

• November 27, 2015: This false-color image of south Khartoum in Sudan (Figure 30) was one of the first from Sentinel-2A, acquired on 28 June 2015, five days after the spacecraft arrived in orbit. The scene confirms that Sentinel-2A is doing the job it was designed for: monitoring vegetation. The mission tracks variability in land surface conditions, with its wide swath width and frequent revisits showing how vegetation changes during the growing season. The high-resolution multispectral instrument reveals the area's agricultural condition. 36)

- Part of the Blue Nile River is visible on the upper right corner. The scattered reds bordering the river denote the dense vegetation. In this arid part of the country, much of the agriculture is highly concentrated around the river. Along the Blue Nile, farming patterns recall French-style farms. Every agricultural plot is a distinctive rectangle, with some substantially longer than others. This geometric arrangement allows each plot to be irrigated. The main crops include sorghum, wheat, cotton, sunflower groundnuts, vegetables, fruit trees, and alfalfa.

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Figure 30: The Sentinel-2A scene lies just south of the capital, Khartoum, the country's second largest city. It is located between the White Nile River on the left (not visible) and the Blue Nile River on the right, which flows west from Ethiopia (image credit: Copernicus Sentinel data (2015)/ESA)

• November 20, 2015: The image of Merida (Figure 31) was acquired by Sentinel-2A. Merida, with a population of 60,000, is the capital of the autonomous community of Extremadura, in western Spain. Owing to the satellite's high-resolution multispectral instrument, the color distinction of this arid area is obvious. The greys are the small towns of Montijo and Santa Amalia, on either side of Merida, while the scattered greens are fields of different crops and plants, crisscrossed with canals. The brown and reddish are the typical colors of fields without vegetation, which was the case when the image was captured in August 2015. 37)

- The Guadiana River is also visible, crossing through the centre of the image, along with various smaller bodies of water, all fundamental for irrigating the many fields in such a dry area. The land is divided into estates, where vineyards and olive groves are cultivated along with wheat. Dry farming predominates, with winter wheat and barley as major crops.

- In the lower central part of the image, the small town of Almendralejo is visible, situated in a brownish area. Here the local agriculture features extensive cereals, fruit and grapes, with many vineyards around the town, where a local red wine and brandy are produced.

- Sitting on the north bank of the Guadiana River, Merida was designated a UNESCO World Heritage site in 1993 because of its various archaeological remains. Founded by the Romans in 25 BC, the town still has many Roman remains. A granite bridge, the longest of all Roman bridges still used by pedestrians, is one of the major remains. North of Merida, the Proserpina Dam is visible, a large Roman reservoir that carried water to the town by a magnificent aqueduct, of which there are extensive remains.

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Figure 31: True-color image of Merida in western Spain, acquired by Sentinel-2A on August 11, 2015 (image credit: Copernicus Sentinel data (2015)/ESA)

• November 13, 2015: Figure 32 is a false-color image featuring the city of Qingdao and its surroundings, in China's eastern Shandong province. A major cultural center, Qingdao is home to the Ocean University of China and other higher education facilities. It is also one of China's main hubs for marine science and technology. Qingdao is located on the south coast of the Shandong Peninsula, at the eastern entrance to Jiaozhou Bay. Off the Yellow Sea, it is one of the best natural harbors in China. 38)

- Owing to the satellite's multispectral high-resolution instrument, one can clearly make out boats entering and exiting the bay, along with the impressive 26.7 km long Jiaozhou Bay Bridge running across the entire bay. As of 2012, the Guinness World Records lists the bridge as the world's longest bridge over water.

- Various aquacultures are visible along the coast of the bay, including the farming of fish, crustaceans, molluscs and aquatic plants.

- Towards the top of the image, one can make out a big body of water, the Jihongtan Reservoir, the biggest of the various reservoirs featured.

- Owing to the image processing, vegetation appears in reds scattered throughout the entire scene, showing how fertile and lush the region is.

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Figure 32: This false-color image of Qingdao, China was captured by Sentinel-2A on August 21, 2015 (image credit: Copernicus Sentinel data (2015)/ESA)

• November 6, 2015: The capital of Egypt, Cairo is one of the largest cities in Africa. It has existed for over 1000 years on the same spot on the Nile River banks. Located in the northeastern part of the country, Cairo is the passage to the Nile delta. The Nile River is the father of African rivers and the longest river in the world. With a length of some 6650 km, it rises south of the equator and flows northwards through northeastern Africa, draining into the Mediterranean Sea. 39)

- The river is the cause of the strong contrasts we see in the image. The river's fertility allowed the Egyptians to thrive despite the arid surrounding desert. It has always delivered the necessary water to transform the desert into a lush garden, where produce such as tomatoes, potatoes, sugar cane, rice and even cotton are grown. The Nile Delta, in fact, ranks among the world's most fertile farming areas. The sharp borderline between green fields and the yellow–brown desert is clear. Notice how the area is greener on the west side – the terrain is flatter, so more easily irrigated than the higher terrain to the east.

- The city of Cairo shows striking contrasts. Along the well-irrigated shoreline, the green reveals the thick vegetation, while the grey areas denote the dense city. In the older areas to the east, however, beneath the foothills of the Eastern Desert and the rocky Muqattam Hills, brown and ochre are the dominant colors.

- The city continuously mixes ancient and new. The Pyramids of Giza, erected on a rocky plateau on the west bank of the Nile, stand at the southwestern edge of the city, while the world's oldest surviving obelisk in the northeast marks the site of Heliopolis, a suburb of Cairo some 10 km from the city center.

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Figure 33: This image from Sentinel-2A, acquired on August 13, 2015, features Cairo and portions of the Nile Delta in Egypt (image credit: Copernicus Sentinel data (2015)/ESA)

• October 23, 2015: Mexico City (Figure 34), the home of nearly nine million people, is the densely populated, high-altitude capital of Mexico.The optical camera of Sentinel-2A clearly shows the difference between the densely built city center and the vast surrounding vegetation. The brownish-grey patch in the right corner of the central part of the image is a flat area with some agriculture, crisscrossed by canals. Mexico International Airport is also visible, and further along the dark green rectangle is Lake Nabor Carrillo. This is a reservoir, encompassing more than 14,163 ha, which is 41 times larger than New York's Central Park. 40)

- Mexico City is located in the Valley of Mexico, also called the Valley of Anáhuac, a large valley in the high plateaus in the center of Mexico, at an altitude of 2240 m. This valley is in the Trans-Mexican Volcanic Belt, which is at least 2200 m above sea level. Mountains and volcanoes surround it, with elevations reaching beyond 5000 m.

- The city rests mainly on the heavily saturated clay of what used to be Lake Texcoco. This soft base is collapsing through the over-extraction of groundwater, and the city has sunk as much as nine meters in some areas since the beginning of the 20th century.

- Clouds are scattered throughout the image, under which lie various national parks and some of the still-active volcanoes, such as Popocatépetl at 5426 m.

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Figure 34: This natural-color Sentinel-2A image features Mexico City and its surroundings, acquired on August 6, 2015 (image credit: Copernicus Sentinel data (2015)/ESA)

• Figure 35 was released by ESA on October 16, 2015 showing the beautiful true-color image of the Red Sea coral reefs off the coast of Saudi Arabia. This vast, desolate area in the very northern corner of the Red Sea is bordered by the Hejaz Mountains to the east. The area was once crisscrossed by ancient trade routes that played a vital role in the development of many of the region's greatest civilizations. 41)

- The Red Sea separates the coasts of Egypt, Sudan and Eritrea to the west from those of Saudi Arabia and Yemen to the east. It contains some of the world's warmest and saltiest seawater. With hot sunny days and the lack of any significant rainfall; dust storms from the surrounding deserts frequently sweep across the sea. This hot dry climate causes high levels of evaporation from the sea, which leads to the Red Sea's high salinity.

- The Red Sea is just over 300 km across at its widest point, about 1900 km long and up to 2600 m deep. Much of the immediate shoreline is quite shallow, dotted with coral reefs along most of the coast — making excellent diving spots in many areas. The Red Sea lies in a fault separating two blocks of Earth's crust – the Arabian and African plates.

- Its name derives from the color changes in the waters. Normally, the Red Sea is an intense blue–green. Occasionally, however, extensive algae blooms form and when they die off they turn the sea a reddish-brown color.

- Navigation in the Red Sea is difficult. The shorelines in the northern half provide some natural harbors, but the growth of coral reefs has restricted navigable channels and blocked some harbor facilities. Shallow submarine shelves and extensive fringing reef systems rim most of the Red Sea, by far the dominant reef type found here. The lighter blue water depicted in the image means that the water is shallower than the surrounding darker blue water.

- Furthermore, water clarity is exceptional in the Red Sea because of the lack of river discharge and low rainfall. Therefore, fine sediment that typically plagues other tropical oceans, particularly after large storms, does not affect the Red Sea reefs.

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Figure 35: Deep blue Red Sea reefs captured with Sentinel-2A on June 28, 2015 (image credit: Copernicus Sentinel data (2015)/ESA)

• Sept. 18, 2015: The early Sentinel-2A ‘color vision' image of Figure 36 captures part of the Mississippi swamps on the east and west banks of the Mississippi River, south of New Orleans and north of the Mississippi Delta. 42)

- From agricultural monitoring to charting changing lands, images from Europe's Sentinel-2A ‘color vision' satellite can be used for many practical applications and to keep us, and our planet, safe. The red color scattered throughout the image shows the enormous amount of vegetation in the area, while the grey represents the various bodies of water.

- Close to the heart of the snake-like Mississippi River, the image clearly shows the typical French-style fields, with rows of sugar cane, around the towns of Lucy, Edgard and Wallace. On the east bank of the Mississippi lie the towns of LaPlace, Reserve, Lions, Garyville and Mount Airy, each with industries along the river, including a chemical plant, sugar refinery, grain elevators and an oil refinery.

- Bayous are scattered all over the image. A bayou is a Franco-English term for an extremely slow-moving stream or river, marshy lake or wetland. They are commonly found in the Mississippi River Delta, famous within the states of Louisiana and Texas. Though fauna varies by region, many bayous are home to crawfish, certain species of shrimp, other shellfish, catfish, frogs, toads, American alligators and crocodiles, and the alligator snapping turtle.

- Towards the upper left part of the image, under the many clouds, lies Baton Rouge, the capital of Louisiana and its second-largest city. On the eastern bank of the Mississippi River, Baton Rouge is a major industrial, petrochemical, medical, research, motion picture and growing technology center of the American south. The port of Baton Rouge is the ninth largest in the United States in terms of tonnage shipped.

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Figure 36: This MSI image of Sentinel-2A was captured on July 15, 2015 (image credit: Copernicus Sentinel data (2015)/ESA)

• Sept. 11, 2015: The varying shades of red and other colors across the entire image (Figure 37) indicate how sensitive the satellite's multispectral camera is to differences in vegetation cover and chlorophyll content. This is used to provide key information on plant health. The brighter reds indicate more photosynthetically active vegetation, as seen in many of the fields and along the Roveto Valley Abruzzi mountain range in the lower left. 43)

- In the very center of the image, a cloud and its shadow are clearly visible over the plain. On the central left side, one can make out an industrial area, whereas the town of Avezzano is just further north.

- The entire area in the center is where the Fucino Lake used to be. The Romans founded settlements on its banks as the lake provided fertile soil and a large quantity of fish. However, the lake was believed to harbor malaria, and, not having a natural outflow, it repeatedly flooded the surrounding arable land.

- In 1862 Prince Alessandro Torlonia commissioned a Swiss engineer to drain what was once Italy's third largest lakes. A 6.3 km long and 21 m wide canal was dredged. By 1875 the lake was completely drained, and the resulting plain is one of Italy's most fertile regions today.

- A canal is clearly visible running horizontally across the center of the image.

- In the lower-right section of the plain is a cluster of dots surrounded by fields: the Fucino Space Center, one of the largest civil space centers in the world, a node for missions operations. The dots are the 100 antennas sited on an extension of 370 ,000 m2. Fucino also hosts one of the control centers that will manage the 30 satellites and the operational activities of Galileo, the European satellite navigation system.

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Figure 37: This Sentinel-2A false color image, captured on July 8, 2015, shows agricultural structures in the Abruzzo region of central Italy (Copernicus Sentinel data (2015)/ESA)

• Sept. 4, 2015: The Sentinel-2A satellite has been in orbit for only a matter of weeks, but new images of an algal bloom in the Baltic Sea show that it is already exceeding expectations. Built essentially as a land monitoring mission, Sentinel-2 will also certainly find its way into marine applications. 44)

- Warm weather and calm seas this August have increased the amount of biological activity in the central Baltic Sea, with the Finnish algae monitoring service Alg@line reporting a dominance of cyanobacteria in the region at this time.

- The Baltic Sea faces many serious challenges, including toxic pollutants, deep-water oxygen deficiencies, and toxic blooms of cyanobacteria affecting the ecosystem, aquaculture and tourism. The situation was so bad that in 1974 the Helsinki Convention for the Protection of the Marine Environment of the Baltic Sea Area was created to improve the state of the sea. Since then, the health of the Baltic Sea has improved dramatically.

- Blooms in the Baltic Sea usually appear as a green–yellow soup or a mass of blue–green threads along density gradients within the sea. The streaks and filaments, eddies and whirls of biological activity are clearly visible in these new images.

- Cyanobacteria have qualities similar to algae and thrive on phosphorus in the water. High water temperature and sunny, calm weather often lead to particularly large blooms that pose problems to the ecosystem and, therefore, aquaculture and tourism. Toxicity varies between different species, but can also vary within the same species. Because of this, several teams monitor the status of blooms in the region using ships.

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Figure 38: Sentinel-2A captured this detailed image of an algal bloom in the middle of the Baltic Sea on 7 August 2015 (image credit: Copernicus Sentinel data (2015)/ESA)

Legend to Figure 38: The image, which has a spatial resolution of 10 m, reveals the bloom in exquisite detail as well as a ship heading into the ‘eye of this algal storm'. The ship's wake can be seen as a straight dark line where the bloom has been disturbed by the ship's propellers.

• Sept. 4. 2015: Figure 39 features Lake Amadeus in Australia's desert. The image shows the variety of the sandy, rocky and salty formations within the lake. Around 180 km long and 10 km wide, Amadeus is the largest salt lake in the Northern Territory, just 50 km north of Uluru/ Ayers Rock. 45)

- Lake Amadeus contains up to 600 million tons of salt. However, harvesting is not feasible because of its remote location. Owing to the aridity of the area, the surface of Lake Amadeus is often a dry salt crust. When rainfall is sufficient, it becomes part of an east-flowing drainage system that eventually connects to the Finke River.

- A UNESCO World Heritage Site and one of Australia's most recognizable landmarks, Uluru/Ayers Rock is a large sandstone rock formation standing 348 m high, rising 863 m above sea level and with a circumference of 9.4 km.

- Also clearly visible in the lower-central part of the image are the Petermann Ranges. These mountains run 320 km across the border between Western Australia and the southwest corner of the Northern Territory. Their highest point is 1158 m above sea level. The range was formed about 550 million years ago as compression folded a section of Earth's crust.

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Figure 39: Lake Amadeus in Australia's Northern Territory, captured on July 13, 2015 with the Sentinel-2A spacecraft (image credit: Copernicus Sentinel data (2015)/ESA)

• July 31, 2015: The largest lake in Figure 40 is the southern part of Lake Maggiore. Straddling the border of Italy's Lombardy and Piedmont regions – with its northern end in Switzerland (not visible) – the lake covers an area of over 210 km2. Its outlet, the Ticino river, snakes south past the Milan–Malpensa Airport at the bottom of the image. 46)

- Near the center of the image is the glacial Lake Varese, appearing in lighter blue when compared to the other lakes in the image. This demonstrates Sentinel-2's ability to measure differences in the conditions of inland water bodies – one of the mission's main applications along with land cover, agriculture and forestry.

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Figure 40: Sentinel-2A image of lakes on the southern side of the Italian Alps, acquired on June 27, 2015 (image credit: Copernicus Sentinel data (2015)/ESA)

• July 27, 2015: From agricultural monitoring to charting changing lands, early images from Europe's new Sentinel-2A satellite show how the ‘color vision' mission's critical observations can be used to keep us and our planet safe. Only one example from several land-monitoring applications is shown here. 47)

- Sentinel-2's imager has 13 spectral bands, from the visible and the near-infrared to the shortwave infrared at different spatial resolutions, taking land monitoring to an unprecedented level. In fact, it is the first optical Earth observation mission of its kind to include three bands in the ‘red edge', which provide key information on the state of vegetation. - This was demonstrated by Pierre Defourny from the University of Louvain in Belgium, who showed how the satellite is even able to discriminate between different crops, showing an example of sunflowers and maize growing near Toulouse in France.

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Figure 41: In this image from 6 July 2015 acquired near Toulouse, France, the satellite's multispectral instrument was able to discriminate between two types of crops: sunflower (in organge) and maize (in yellow), image credit: Copernicus Sentinel data (2015)/ESA/University of Louvain/CESBIO

• July 10, 2015: More than 90% of Algeria, which is the largest country in Africa (2,381,741 km2 ), is covered by the Sahara desert. Major oil and natural gas deposits lie beneath the Sahara, contributing to Algeria's position as one of the wealthiest African nations. 48)

- In its entirety, the Sahara stretches from the Atlantic Ocean to the Red Sea and is centered on the Tropic of Cancer. It is the world's largest hot desert, covering an area of about 9 million km2 over parts of Algeria, Chad, Egypt, Libya, Mali, Mauritania, Morocco, Niger, Tunisia and Sudan.

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Figure 42: The sandy and rocky terrain of the Sahara desert in central Algeria was captured in this image by the Sentinel-2A satellite, also acquired on June 27, 2015 and delivered in the first scan of Earth with the MSI instrument (image credit: Copernicus Sentinel data (2015)/ESA)

Legend to Figure 42: The area pictured is about 90 km south of the El Ménia oasis – also known as El Goléa – in Algeria's Ghardaïa province. Running north to south just left of the large sand dune at the center, one can see a road that connects El Ménia to Ain Salah in the south, which was once an important link on the trans-Saharan trade route.

The heat and lack of water render vast desert areas highly unwelcoming, making satellites the best way to observe these environments on a large scale. In addition, optical imagery of deserts from space is arguably the most fascinating: the diversity and untouched state of these landscapes produce unique and striking scenes.

• June 29, 2015: Just four days after being lofted into orbit, Europe's Sentinel-2A satellite delivered its first images of Earth, offering a glimpse of the ‘color vision' that it will provide for the Copernicus environmental monitoring program. 49)

- With a swath width of 290 km, the satellite's first acquisition began in Sweden and made a strip-like observation through central Europe and the Mediterranean, ending in Algeria. The data were relayed in real time to Italy's Matera ground station, where teams eagerly awaited their arrival for processing.

- While northern and central Europe were mostly cloudy, Italy's typical sunny weather allowed the teams to get their first glimpse of the multispectral instrument's capabilities over the northwestern part of the country and the French Riviera — and they were excited by what they saw. With a ground resolution of 10 m per pixel, the images show individual buildings in Milan, agricultural plots along the Po River, and ports along the southern French coast.

- "This new satellite will be a game changer in Earth observation for Europe and for the European Copernicus program," said Philippe Brunet, Director for Space Policy, Copernicus and Defence at the European Commission. The Director of ESA's Earth Observation Programs, Volker Liebig, commented, "Sentinel-2 will enable us to provide data for the program's land monitoring services and will be the base for a wide spectrum of applications reaching from agriculture to forestry, environmental monitoring to urban planning."

- The MSI (Multispectral Imager) is being calibrated during the commissioning phase – which will take about three months to complete – but the quality of these first images already exceeds expectations. In addition to demonstrating the imager's high resolution, these initial data also foreshadow the mission's land-monitoring applications in areas such as agriculture, inland and coastal waters and land-cover mapping.

- The imager's 13 spectral bands, from the visible and the near infrared to the shortwave infrared at different spatial resolutions, take land monitoring to an unprecedented level. In fact, Sentinel-2A is the first optical Earth observation mission of its kind to include three bands in the ‘red edge', which provide key information on the state of vegetation.

- This weekend's activities also demonstrated that the operational processor works flawlessly, paving the way for the mission's systematic data generation to come.

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Figure 43: First MSI image of Sentinel-2A, acquired on 27 June 2015, just four days after launch, covering the Po Valley, framed by the Alps in the north and the coastal mountains of France and Italy in the south (image credit: Copernicus data (2015)/ESA)

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Figure 44: This close-up of Milan is a subset from the first image of Figure 43 of Sentinel-2A, acquired on 27 June 2015 (image credit: Copernicus data (2015)/ESA)

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Figure 45: A close-up of an area in the Po Valley — showing Pavia (center) and the confluence of the Ticino and Po rivers — is a subset of Figure 43 from the Sentinel-2A, acquired on 27 June 2015. Processed using the high-resolution infrared spectral channel, the satellite's instrument will provide key information on crop type and health, assisting in food security activities (image credit: Copernicus data (2015)/ESA)

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Figure 46: This close-up of France's southern coast from Nice airport (lower left) to Menton (upper right) is a subset of Figure 43 from the Sentinel-2A, acquired on June 27, 2015. This false color image was processed including the instrument's high-resolution infrared spectral channel (image credit: Copernicus data (2015)/ESA, Ref. 49)

• Figure 47 of northwest Sardinia is featured on ESA's Earth from Space video program; it originates also from the very first acquisition by the Sentinel-2A satellite on June 27. 50)

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Figure 47: This image of Sardinia, acquired on June 27, 2015, covers section of the island's northwestern Sassari province, with parts of the coast visible along the left side and bottom. Agricultural fields dominate the inland, with a large area of vineyards at the center of the image (image credit: Copernicus data (2015)/ESA)

Legend to Figure 47: The varying shades of red and other colors across the entire image indicate how sensitive the multispectral instrument is to differences in chlorophyll content. This is used to provide key information on plant health and, for this image, the brighter reds indicate healthier vegetation. In the lower left section, one can see a large hilly area with significant vegetation – indicated by the red coloring. However, a bright white/light-blue section of this area shows where the hills have been cut into for surface mining.

• LEOP (Launch and Early Orbit Phase) formally ended on June 26, 2015. The mission control team dealt with several typical problems seen in any launch, including issues with a sticky valve, a star tracker and a GPS unit. These have been resolved and the satellite is now in excellent health. "We conducted our first orbital maneuver using the Sentinel-2A thrusters yesterday, and this went exactly as planned," said Spacecraft Operations Manager Franco Marchese. "Overall, this LEOP has gone very smoothly and we are well en route to achieving our reference orbit within next week." 51)

- LEOP is being followed by the 3-month commissioning phase. The two main objectives now will be to assess and characterize the spacecraft performance. In parallel, calibration and validation activities will be conducted for the MSI (Multispectral Imager) payload, involving CNES and ESA. In addition, the new optical data communication capability will be commissioned by DLR and Tesat Space.

- The spacecraft will also be readied to start the routine acquisition of high-resolution images of Earth's land surfaces, large islands, inland and coastal waters on a ten-day revisit cycle, which will drop to five days when the constellation with the Sentinel-2B satellite is implemented in 2016.

• June 23, 2015: Just a few minutes after separation from its Vega launcher on 23 June, the Sentinel-2A satellite automatically activated its solar array and transmitter, oriented itself into an Earth-pointing mode, and started transmitting 'telemetry' – onboard status signals – to the ground. Receipt of these first crucial data from the new mission marked the start of an intensive phase in the ESOC MOC (Mission Control Center) in Darmstadt, Germany. 52)

- For the next several days, an extended team of spacecraft engineers, systems specialists, flight dynamics experts and ground station technicians will shepherd Sentinel-2A through LEOP Launch and Early Orbit Phase).

 


1) "China's Tian Shan mountains," ESA, Earth observation image of the week, Dec. 23, 2016, URL: http://m.esa.int/spaceinimages/Images/2016
/12/China_s_Tian_Shan_mountains

2) "Agricultural monitoring in Spain," ESA, Dec. 20, 2016, URL: http://m.esa.int/spaceinimages/Images/2016/12/Agricultural_monitoring_in_Spain

3) "Seville, Spain," ESA, Earth observation image of the week, Dec. 16, 2016, URL: http://m.esa.int/spaceinimages/Images/2016/12/Seville_Spain

4) "Switzerland," ESA, Earth observation image of the week, Dec. 2, 2016, URL: http://www.esa.int/spaceinimages/Images/2016/12/Switzerland

5) "Chiapas forest land-cover map," ESA, Nov. 25, 2016, URL: http://m.esa.int/spaceinimages/Images/2016/11/Chiapas_forest_land-cover_map

6) Valerie Fernandez, Claudia Isola, Bianca Hoersch, Ferran Gascon, Thierry Tréma, "Sentinel-2A: MultiSpectral Instrument first in-orbit performance," Proceedings of the ICSO 2016 (International Conference on Space Optics), Biarritz, France, 18-21 October, 2016, URL: http://esaconferencebureau.com/custom/icso/2016/index.htm

7) "Gibson Desert," ESA, Earth observation image of the week, Nov. 18, 2016, URL: http://m.esa.int/spaceinimages/Images/2016/11/Gibson_Desert

8) "Sentinel sees us," ESA, URL: http://m.esa.int/spaceinimages/Images/2016/11/Sentinel_sees_us

9) "Putorana Plateau, Siberia," ESA, Earth observation image of the week. Oct. 28, 2016, URL: http://m.esa.int/spaceinimages/Images/2016/10/Putorana_Plateau_Siberia

10) "Kathmandu, Nepal," ESA, Earth observation image of the week, Oct. 21, 2016, URL: http://m.esa.int/spaceinimages/Images/2016/10/Kathmandu_Nepal

11) "Ouarkziz crater," ESA, Sept. 30. 2016, URL: http://m.esa.int/spaceinimages/Images/2016/09/Ouarkziz_crater

12) "Fire-scarred Madeira," ESA, Earth observation image of the week, Sept. 14, 2016, URL: http://m.esa.int/spaceinimages/Images/2016/09/Fire-scarred_Madeira2

13) "Barents bloom," ESA, Sept. 9, 2016, URL: http://m.esa.int/spaceinimages/Images/2016/08/Barents_bloom

14) "Earth from Space: Barents bloom," ESA Earth from Space video program, Sept. 9, 2016, URL: http://m.esa.int/spaceinvideos/Videos/2016/09/Earth_from_Space_Barents_bloom

15) "Massive and Mysterious Ice Fall in Tibet," NASA Earth Observatory, Sept. 7, 2016, URL: http://earthobservatory.nasa.gov/IOTD/view.php?id=88677&src=eoa-iotd

16) "Nine killed by avalanche in Tibet," China Daily, July 18, 2016, URL: http://www.chinadaily.com.cn/china/2016-07/18/content_26128513.htm

17) "Upsala Glacier," ESA image of the week, Sept. 2, 2016, URL: http://m.esa.int/spaceinimages/Images/2016/08/Upsala_Glacier

18) "Chile's salt flat," ESA, May 27, 2016, URL: http://m.esa.int/spaceinimages/Images/2016/05/Chile_s_salt_flat

19) "Rub al Khali," ESA Earth observation image of the week, May 20, 2016, URL: http://www.esa.int/spaceinimages/Images/2016/05/Rub_al_Khali

20) "Sun glitter reveals coastal waves," ESA, May 19, 2016, URL: http://www.esa.int/Our_Activities/Observing_the_Earth
/Copernicus/Sentinel-2/Sun_glitter_reveals_coastal_waves

21) "African mosaic," ESA, May 18, 2015, URL: http://www.esa.int/spaceinimages/Images/2016/05/African_mosaic

22) "Czechered landscape," ESA, May 9, 2016, URL: http://www.esa.int/spaceinimages/Images/2016/05/Czechered_landscape

23) "Colorful Naukluft," ESA, Earth observation image of the week, April 29, 12016, URL: http://www.esa.int/spaceinimages/Images/2016/04/Colourful_Naukluft

24) "Australia ensured access to Sentinel data," ESA, March 31, 2016, URL: http://www.esa.int/Our_Activities/Observing_the_Earth
/Copernicus/Australia_ensured_access_to_Sentinel_data

25) "Lake Amadeus," ESA, March 30, 2016, URL: http://www.esa.int/spaceinimages/Images/2016/03/Lake_Amadeus

26) "Etosha," ESA Earth observation image of the week, March 25, 2016, URL: http://www.esa.int/spaceinimages/Images/2016/03/Etosha

27) "Sentinel data wanted," ESA, March 15, 2016, URL: http://www.esa.int/Our_Activities/Observing_the_Earth/Sentinel_data_wanted

28) Jon Campbell, "USGS Partners with European Space Agency to Deliver Copernicus Earth Data," March 15, 2016, URL: http://landsat.gsfc.nasa.gov/?p=12194

29) "Eastern Desert of Egypt," ESA Earth observation image of the week, Feb. 26, 2016, URL: http://www.esa.int/spaceinimages/Images/2016/02/Eastern_Desert

30) "Madrid," ESA, Feb. 12, 2016, URL: http://www.esa.int/spaceinimages/Images/2016/02/Madrid

31) "ESA selects Airbus Defence and Space for two new Sentinel-2 satellites," Airbus DS, January 26, 2016, URL: http://www.space-airbusds.com/en/press_centre/esa-selects-airbus-defence
-and-space-for-two-new-sentinel-2-satellites.html

32) "Colors of the Persian Gulf," ESA, Jan. 22, 2016, URL: http://www.esa.int/spaceinimages/Images/201
6/01/Colours_of_the_Persian_Gulf

33) "Mongolian marvel," ESA image of the week, release on Dec. 18, 2015, URL: http://www.esa.int/spaceinimages/Images/2015/12/Mongolian_marvel

34) "French Portrait," ESA Image of the week released on Dec. 11, 2015, URL: http://www.esa.int/spaceinimages/Images/2015/12/French_portrait

35) "Sentinel-2A products available in the Data Hub," ESA, Dec. 3, 2015, URL: https://earth.esa.int/web/guest/missions/esa-operational-eo-missions/
sentinel-2/news/-/article/sentinel-2a-products-available-in-the-data-hub

36) "Khartoum, Sudan," ESA Image of the week released on Nov. 27, 2015, URL: http://www.esa.int/spaceinimages/Images/2015/11/Khartoum_Sudan

37) "Merida, Spain," ESAImage of the week , Nov. 20, 2015, URL: http://www.esa.int/spaceinimages/Images/2015/11/Merida_Spain

38) "Qingdao, China," ESA Image of the week, released on Nov. 13, 2015, URL: http://www.esa.int/spaceinimages/Images/2015/11/Qingdao_China

39) "Cairo, Egypt," ESA, Earth observation image of the week, Nov. 6, 2015, URL: http://www.esa.int/spaceinimages/Images/2015/11/Cairo_Egypt

40) "Mexico City," ESA Earth observation image of the week, released on Oct. 23, 2015, URL: http://www.esa.int/spaceinimages/Images/2015/10/Mexico_city

41) "Deep blue Red Sea reefs," ESA, Earth observation image of the week, October 16, 2015, URL: http://www.esa.int/spaceinimages/Images/2015/10/Deep_blue_Red_Sea_reefs

42) "Mississippi swampland," ESA,'Earth observation image of the week,' released on Sept. 18, 2015, URL: http://www.esa.int/spaceinimages/Images/2015/09/Mississippi_swampland

43) "Avezzano, Italy," ESA, Sept. 11, 2015, URL: http://www.esa.int/spaceinimages/Images/2015/09/Avezzano_Italy

44) "Sentinel-2 catches the eye of algal storm," ESA, Sept. 4, 2015, URL: http://www.esa.int/Our_Activities/Observing_the_Earth/
Copernicus/Sentinel-2/Sentinel-2_catches_eye_of_algal_storm

45) "Australian desert," ESA, Sept. 4, 23015, URL: http://www.esa.int/spaceinimages/Images/2015/09/Australian_desert

46) "Northern Italy," ESA, Earth observation image of the week, July 31, 2015, URL: http://www.esa.int/spaceinimages/Images/2015/07/Northern_Italy

47) "First applications from Sentinel-2A," ESA, July 22, 2015, URL: http://www.esa.int/Our_Activities/Observing_the_Earth/
Copernicus/Sentinel-2/First_applications_from_Sentinel-2A

48) "Central Algeria," ESA, Earth observation image of the week, July 10, 2015, URL: http://www.esa.int/spaceinimages/Images/2015/07/Central_Algeria

49) "Sentinel-2 delivers first images," ESA, June 29, 2015, URL: http://www.esa.int/Our_Activities/Observing_the_Earth/
Copernicus/Sentinel-2/Sentinel-2_delivers_first_images

50) "Northwest Sardinia," ESA, July 3, 2015, URL: http://www.esa.int/spaceinimages/Images/2015/07/Northwest_Sardinia

51) "Sentinel-2A completes critical first days in space," ESA, June 26, 2015, URL: http://www.esa.int/Our_Activities/Observing_the_Earth/
Copernicus/Sentinel-2/Sentinel-2A_completes_critical_first_days_in_space

52) "Under control," ESA, June 23, 2015, URL: http://www.esa.int/spaceinimages/Images/2015/06/Under_control
 


The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: "Observation of the Earth and Its Environment: Survey of Missions and Sensors" (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates (herb.kramer@gmx.net).