Image of the week-Earth from Space: Historical view

Image of the week-Earth from Space: Historical view

 By ESA

(The first MERIS observation captured the huge phytoplankton patch produced by the ‘upwelling’ mechanism along the west coast of Africa near Mauritania. The unprecedented resolution allows fine-scale structures to be detected. In such upwelling areas, northeast trade winds bring deep and nutrient-rich water to the surface, feeding phytoplankton. Changes in climate affect the intensity of the upwelling with important consequences for marine ecosystems, fisheries and local economies.

One important task for MERIS is to provide overviews of the dynamics of upwelling areas and their primary production. This, in turn, could improve management of fish stocks within sustainable limits. Another important task for MERIS is to provide information on carbon fixation through photosynthesis within the global ocean for a better understanding of the carbon cycle.

 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 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)

 West Africa’s coast along the Atlantic Ocean is pictured in this first image from Envisat’s MERIS instrument nearly a decade ago.

This week, Envisat celebrated ten years in orbit. The Medium Resolution Imaging Spectrometer – or MERIS – on board the satellite was developed to measure sea colour in oceans and coastal areas, although it has been used for a variety of additional applications over the years.

 Envisat carries ten sensors, collecting imagery and other data on Earth’s land, oceans, atmosphere, temperature and ice cover.

The first batch of data from the satellite in March 2002 was acquired via the Kiruna station in Sweden and processed at ESA’s ESRIN establishment in Italy and other centres throughout Europe.

 In this first image from MERIS on 22 March 2002, a very dry desert directly borders the ocean teeming with life. To the south, a high concentration of phytoplankton was detected along the coasts of Senegal, the Gambia and Guinea-Bissau.

 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 Earth’s oceans, phytoplankton concentration is extremely low. However, in ‘upwelling areas’ like the one pictured here, the ocean becomes rich in minerals from the mixing of surface waters with deeper waters.

 The most important fishing grounds can be found in these upwelling areas. Climate change has an effect on the intensity and geographical position of these areas, which, in turn, has important consequences for the fishing industries and those who depend on them.

 Also evident in this image is the transition from the dry desert lands in the north through the savannah and to tropical vegetation in the south, which receives more rainfall. MERIS can monitor land use that leads to increased erosion and soil loss.  

The Image of the Week is featured on ESA Web-TV, broadcast online every Friday at 10:00 CET.

©Typologos.com 2012. The article belongs to ESA.Credit of image and belongs to ESA.