Topic 1f - ENSO

The El Niño Southern Oscillation (ENSO) is a coupled atmosphere-ocean phenomenon with wide reaching impacts. It can be observed through satellite sensed sea surface temperature and height.

ENSO impacts:

  • Droughts

  • Floods

  • Changes to marine environments, with implications for food security (agriculture, fisheries, aquaculture).

ENSO shows how interconnected the Earth system is. For example, fish catches off the coast of Peru are influenced by large scale interactions between the oceans and atmosphere over the Pacific.

ENSO is typically observed as anomalous patterns of SSH (sea surface height) and SST (sea surface temperature), but its impact on biology can also be observed by satellites. M-FR has been using ocean colour data to look at the biological response to ENSO – important from a fisheries perspective. Detecting changes in the frequency or intensity of ENSO events relies on the availability of long term, consistent data, such as that available from Copernicus and CMEMS.


El Niño is an ocean phenomenon of the tropical Pacific. In a strong El Niño year sea surface height in the Eastern Pacific can rise by as much as 30cm, the water is much warmer than usual, and there is a dramatic drop in phytoplankton productivity off the coast of Peru. This impacts food supply of virtually all organisms in the coastal current ecosystem, and fish catches are much lower than normal. Heavy rains fill coastal deserts with lakes, and vegetation sprouts where there is usually bare soil.

El Niño is a fundamental part of Earth’s climate, and being able to predict when it will occur is important for seasonal weather prediction. The problem is how to foresee an El Niño many months or years in advance. By the time coastal temperatures rise, El Niño is already well on its way.

Featured Educators:

  • Dr Marie-Fanny Racault

Explore the data

EUMETSAT Oceans MOOC Data Viewer

View featured satellites on the satellite tracking app

Don’t forget you can download the video and transcript with the links on the right.


El Nino Equitorial Ocean conditions

Tropical weather pattern across the equator during El Niño.

Animation: El Nino, La Nina

Sea Surface Temperature Anomaly & Ocean Color variations during El Nino vs. La Nina.

To view the animation click on the link below, and you will be taken to the NASA website.

Regionally-differentiated El Niño impacts

Phytoplankton respond within hours to days to perturbations in environmental conditions. This makes them ideal indicators to study the first-level biological responses to climate variability and change.

The prevalence of one El Niño mode over another can have profound impacts on the marine ecosystem structure and functioning – affecting trophic interaction (fisheries) and carbon fluxes

Two types of El Niño

The responses of phytoplankton to El Niño variability and the driving physical processes are characterised in the global oceans based on ocean-colour, SST, sea level and wind observations.
We observe regionally different patterns in the response of phytoplankton and physical processes to two extreme types of El Niño

ENSO effects

Weather impacts of ENSO

El Nino

Sea level anomalies for August 1997 and 2015