Kumar Bahukhandi
The decline in chlorophyll-a—a key indicator of phytoplankton abundance and marine productivity—has coincided with a dramatic shift in ocean-surface winds.(Picture:X)
The decline in chlorophyll-a—a key indicator of phytoplankton abundance and marine productivity—has coincided with a dramatic shift in ocean-surface winds.
Nellore:India’s EOS-06/Oceansat-3 satellite has captured clear signs of the developing El Niño and its impact on marine productivity across the tropical Pacific Ocean, offering fresh insights into the complex relationship between ocean winds, upwelling, and climate.
An analysis by the National Remote Sensing Centre (NRSC) of ISRO, using data from the satellite’s Ocean Colour Monitor-3 (OCM-3) and Scatterometer sensors, has revealed a marked decline in surface chlorophyll-a concentration during June 2026, compared with observations from neutral ENSO (El Niño-Southern Oscillation) years.
The decline in chlorophyll-a—a key indicator of phytoplankton abundance and marine productivity—has coincided with a dramatic shift in ocean-surface winds. The prevailing easterly winds have weakened and reversed to westerlies, disrupting the normal equatorial upwelling that brings nutrient-rich waters from the ocean depths to the surface.
The satellite observations show that the region of elevated chlorophyll-a progressively contracted westward between April and June 2026, providing further evidence of weakening equatorial upwelling as El Niño developed.
According to ISRO, the combined observations from OCM-3 and the EOS-06 Scatterometer demonstrate strong coupling between atmospheric winds and biological processes in the equatorial Pacific. If El Niño intensifies further, as forecast, the low-chlorophyll region could become increasingly pronounced.
ISRO said on Thursday that the satellite observations complement the World Meteorological Organization’s outlook, which had estimated an 80 per cent probability of El Niño conditions developing during June-August 2026. By late July, the WMO reported that the event is intensifying and is expected to strengthen further during August-October.
The findings underline how India’s space-based ocean-monitoring capabilities are helping scientists track not only atmospheric and oceanic changes, but also their consequences for marine ecosystems and global climate.
