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The Mystery of El Niño Diversity

Have you ever heard of El Niño? El Niño is a disruption of the ocean-atmosphere system in the equatorial Pacific Ocean.  This disruption impacts weather and climate around the world. For example, El Niño influences flood and drought conditions in the continental United States and hurricane activity in the Atlantic Basin. It also has implications on biological production and ecosystem dynamics in many regions, such as reproductive failure and mortality of birds, migration of fish and whales, and the collapse of fisheries off South America.

This image shows warm sea surface temperatures (SST) extending across the equatorial Pacific Ocean on December 1, 1997 in association with the 1997-98 El Niño. The image was obtained from PO.DAAC’s Live Access Server (LAS).

This image shows warm sea surface temperatures (SST) extending across the equatorial Pacific Ocean on December 1, 1997 in association with the 1997-98 El Niño. The image was obtained from PO.DAAC’s Live Access Server (LAS).

The classic El Niño, or eastern Pacific (EP) El Niño, is characterized by unusually warm ocean temperatures in the eastern equatorial Pacific Ocean. However, since the 1990s, unusually warm ocean temperatures have frequently been observed in the central equatorial Pacific Ocean, leading some researchers to suggest a new type of El Niño has developed.  This new version is referred to by several different names: dateline El Niño, El Niño Modoki, central Pacific (CP) El Niño, or warm-pool El Niño. Examples of the two events and their markedly different ocean temperature signatures are shown for the 1997-98 EP-El Niño and 2009-10 CP-El Niño.

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The images compare SST relative to normal (also referred to as anomalies) associated with the mature phase of the 1997-98 EP-El Niño and 2009-10 CP-El Niño events (in December 1997 and 2009, respectively). SST anomalies reflect the heat content in the mixed layer (approximately upper 50 m). The comparison indicates that the warming associated with the 2009-10 CP-El Niño is more pronounced in the central equatorial Pacific, whereas warming is more pronounced in the eastern equatorial Pacific in the 1997-98 EP-El Niño. The image was provided by PO.DAAC.

El Niño conditions and variations can be detected and monitored through sea surface temprature (SST) observations. One example is NASA’s MODIS sensor on the Terra and Aqua satellites, which provides SST observations of the top millimeter of the ocean surface. SST data is critical to understanding El Niño as well as its impacts on worldwide weather and climate. The Physical Oceanography Distributed Active Archive Center (PO.DAAC) at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. offers numerous SST datasets, as well as the tools to search, subset, extract, and visualize them.

PO.DAAC’s Live Access Server (LAS) allows a user to visualize El Niño events over the entire length of a satellite record, and State of the Ocean (SOTO) allows a user to visualize the ocean state over the past 30-days.

You, too, can work with real NASA data to learn more about El Niño!

Post by Michelle Gierach, project scientist at the Physical Oceanography Distributed Active Archive Center (PO.DAAC) in NASA’s Jet Propulsion Laboratory. (Top image credit: NASA/Goddard Space Flight Center Scientific Visualization Studio)

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