Archive · 12 Sep 2026
ISRO Satellite Detects Pacific Productivity Decline As El Niño Strengthens
ISRO used a satellite called EOS-06, or Oceansat-3, to study the Pacific Ocean.
In June 2026, the satellite saw less chlorophyll-a near the ocean surface.
Chlorophyll-a is found in tiny ocean plants called phytoplankton.
These plants help support many animals in the ocean food chain.
El Niño can weaken or reverse winds over the Pacific.
This can stop deep, cold water carrying nutrients from rising to the surface.
With fewer nutrients, fewer phytoplankton may grow, causing chlorophyll-a levels to fall.
Scientists also saw the area with high chlorophyll become smaller and extend less toward the west.
Weather agencies said El Niño might become very strong, but they cautioned that its exact effects on weather are not guaranteed.
ISRO’s EOS-06, also called Oceansat-3, detected a notable decline in surface chlorophyll-a across the equatorial Pacific during June 2026.
The decline coincided with surface winds shifting from their usual easterly direction toward westerlies.
ISRO compared chlorophyll and wind observations from April through June across 2023, 2024, 2025 and 2026.
Reduced chlorophyll-a indicates weaker phytoplankton growth, which researchers linked to El Niño-related suppression of nutrient-rich ocean upwelling.
Forecasts differed in timing but indicated a potentially strong El Niño, with NOAA assigning a more than 90% chance of a very strong event during late 2026 and early 2027.
- Who
- Scientists at ISRO’s National Remote Sensing Centre analyzed EOS-06 satellite observations, with forecasts also issued by the World Meteorological Organization and NOAA.
- What
- The satellite detected declining surface chlorophyll-a, a contraction of high-chlorophyll areas, and a shift in ocean-surface winds as El Niño developed.
- When
- The main decline was observed in June 2026, using comparisons of April-to-June data from 2023 through 2026; forecasts covered late 2026 and early 2027.
- Where
- Across the tropical and equatorial Pacific Ocean.
- Why
- El Niño-related weakening and reversal of surface winds reduced the upwelling of cold, nutrient-rich water, limiting phytoplankton growth.
Evidence of a Strongening El Niño
Forecasts Require Caution
Strength of the developing event
Evidence of a Strongening El Niño
ISRO observed falling chlorophyll-a, contracting high-chlorophyll areas and winds shifting toward westerlies, while NOAA reported sea-surface temperature anomalies above 3°C and assigned more than a 90% chance of a very strong El Niño in late 2026 and early 2027.
Forecasts Require Caution
ISRO said the low-chlorophyll region should be assessed alongside future changes in winds, sea-surface temperature, sea-level height, thermocline depth and ocean circulation; the WMO’s earlier outlook gave an approximately 80% chance of El Niño during June–August 2026 rather than confirming a historic event.
Potential weather consequences
Evidence of a Strongening El Niño
El Niño is associated with heatwaves, extreme temperatures and rainfall changes globally, and has historically been linked with weaker monsoons and warmer conditions in parts of India.
Forecasts Require Caution
NOAA stressed that a stronger El Niño raises the likelihood of characteristic effects but does not guarantee extreme weather in every region; other oceanic and atmospheric factors can alter its influence on India’s monsoon.
- Satellite
- EOS-06, also known as Oceansat-3
- Instruments
- Ocean Colour Monitor-3 and EOS-06 Scatterometer
- Analyzing institution
- ISRO’s National Remote Sensing Centre
- Main observation
- Surface chlorophyll-a declined during June 2026
- Wind change
- Surface winds shifted from easterlies toward westerlies
- Comparison period
- April, May and June in 2023, 2024, 2025 and 2026
- Forecast outlook
- NOAA estimated more than a 90% chance of a very strong El Niño during Northern Hemisphere fall and winter 2026–27, while the WMO had earlier estimated about an 80% chance of El Niño during June–August 2026
