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The first Envisat check-up on the Earth

28 March 2002

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MERIS scene viewed in perspective, with African topography derived from ERS-2 altimeter data.

Credits: ESA

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One of the first photos taken by Envisat, ESA's Earth observation satellite in March 2002. The collapse of the Larsen B ice shelf observed on 18 March 2002.

The Antarctic Penininsula has experienced exceptional atmospheric warming over the last decades, triggering the retreat and break-up of the ice shelves. The launch of Envisat occurred just in time to capture the disintegration of the Larsen B ice shelf. This 400 km wide ASAR image of 18 March 2002 (orbit 246) shows that the collapsed ice shelf has fractured into thousands of small icebergs, drifting eastwards into the Weddell Sea. This kind of breakup is quite different from the periodic calving processes taking place 1000 km further south which have led to the presence of the large drifting icebergs seen in the image.

Credits: ESA

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One of the first photos taken by Envisat, ESA's Earth observation satellite in March 2002 - the collapse of the Larsen B ice shelf observed on 18 March 2002.

Over the last decade ERS-1 and -2 have been monitoring changes in the region. Together with ERS data, this image (orbit 250) documents the 100 km retreat of the Larsen B ice shelf. The break-up has now reched the rock faces of the Peninsula itself. Envisat's ASAR will make regular all-weather observations and enable detailed studies of the extent, surface motion and surface melt of all the ice shelves around Antarctica.

Credits: ESA

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Mauritanian Upwelling - MERIS - 22 March 2002

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Small, single-celled phytoplankton play a key role in the marine food chain. They convert sunlight, carbon dioxide and nutrients into carbohydrates on which nearly all life in the ocean depends.

In most parts of the Earth's ocean, phytoplankton concentration is extremely low. However, in “upwelling areas,” deep water is pumped up to the surface by strong winds, such as trade winds blowing parallel to the coast. This deep water is rich in nutrients and as this supplies phytoplankton with the nitrogen, phosphate and silicate they need for their growth, which supports the whole food chain.

The most important fishing grounds can be found in these upwelling areas. When this upwelling process collapses, as for instance off the Peruvian coast during El Nino events, the ecosystem is dramatically disrupted. Climate change has an impact on the intensity and geographical position of upwelling areas, which, in turn, has important consequences to fishing industries and those who depend on them.

Technical Information:
Instrument: MEdium Resolution Imaging Spectrometer (MERIS) on board Envisat
Date of Acquisition: 22 March 2002
Orbit number: 306
Instrument features: Full resolution image (300-meter resolution).
MERIS was designed to measure the concentration of phytoplankton. The colours seen by MERIS indicate the concentration of chlorophyll, the pigment that phytoplankton use for photosynthesis. MERIS can detect chlorophyll concentrations as low as 0.01 microgram, or 1/100 000 000 of a gram, per litre. MERIS data will be used to monitor the worldwide distribution of phytoplankton and to compute primary production.

Credits: ESA

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One of the first photos taken by Envisat, ESA's Earth observation satellite on 22 of March 2002. This MERIS image shows the complex river system inside Casamance with its heavy discharge into the sea. A series of such images are needed to monitor the transport of sediment which arises from inland soil erosion. This scence covers the transition zone between savannah in the north and tropical vegetation in the south. MERIS can also monitor the intensification of land use which leads to increased erosion and soil loss.
Technical Information:
Instrument: MEdium Resolution Imaging Spectrometer (MERIS)
Date of Acquisition: 22 March 2002
Orbit number: 00306
Instrument features: Full resolution image (300-meter resolution). MERIS was designed to measure the concentration of phytoplankton. The colours seen by MERIS indicate the concentration of chlorophyll, the pigment that phytoplankton use for photosynthesis. MERIS can detect chlorophyll concentrations of less than 1/10 000 000 of a gram per litre. MERIS data will be used to monitor the worldwide distribution of phytoplankton and to compute primary production.

Credits: ESA