Less snow, more plankton

The work of a team from the Bigelow Laboratory for Ocean Sciences (Maine), published in the journal Science, made it possible to establish a link between the decrease in snow cover in the Himalayas and the increase in the concentration of phytoplankton in the sea. 'Arabia in the past seven years. The study of the concentration of chlorophyll in the Arabian Sea, funded by NASA, was carried out using data provided by the American satellite OrbView2, on which is mounted the Sea-viewing Wide Field of View Sensor (Sea -WiFS), and by the Japanese satellite ADEOS (ADvanced Earth Observing Satellite) and its Ocean Color Temperature Sensor (OCTS) instrument.

In addition, scientists have in particular used sea surface nemometric measurements provided by the Tropical Rainfall Measuring (TRMM) satellite.
Mission) operated jointly by NASA and the Japanese space agency (JAXA), and in situ temperature measurements with non-reusable bathythermographs. Oceanologists have thus discovered that, since 1997, the concentration of microscopic algae species in the Arabian Sea has grown steadily. In the summer of 2003, it was 350% higher along the coasts and 300% offshore compared to 1997. This spectacular growth would be correlated with a drop in snow cover in the mountain ranges of India. Indeed, it led to a decrease in the quantity of solar rays absorbed therefore a greater difference in temperature and pressure between the Indian continental mass and the oceanic mass in the Arabian Sea.

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Consequently, the air currents due to the summer monsoons from June to September, generated by the pressure differential, increase the intensity of the associated “upwelling” (that is to say a rise in cold waters). , which further promotes the development of phytoplankton and, beyond, boosts the marine ecosystem as a whole.

WT 09 / 05 / 05 (Climate: a message from
the plankton?)


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