Michael Freilich's Sentinel-6 is the latest satellite to contribute to the 30-year sea level record, and researchers are using it to compare this year's El Niño to past El Niños.
The Sentinel-6 Michael Freilich satellite was launched in 2020 and is designed to monitor sea surface height to aid climate research, particularly the El Niño phenomenon. By tracking changes in sea levels, it can provide important data that helps researchers predict global impacts, from rainfall patterns to potential droughts. Source: NASA/JPL-Caltech
Sentinel-6 Michael Freilich monitors sea surface heights in the Pacific Ocean to assess the impact of El Niño. While the 2023 El Niño does not appear to be as strong as 1997 and 2015, it still has the potential to become stronger.
Not all El Niño events are the same. The effects of El Niño vary widely, and satellites like the U.S.-European Sentinel-6 Michael Freilich help predict the effects of these phenomena on a global scale by tracking changes in sea surface height in the Pacific Ocean.
Water expands as it warms, so sea levels tend to be higher where the water is warmer. Higher than normal sea levels and warmer than average ocean temperatures along the equatorial Pacific coast are characteristics of El Niño. These conditions will propagate poleward along the western coast of America. El Niño can bring wetter conditions to the southwestern United States and drought to the western Pacific, including Indonesia. This year's El Niño is still developing, but researchers are looking to recent El Niños for clues about how they form.
The map above shows sea level in the Pacific Ocean in 1997, 2015 and early October 2023, just before El Niño. Above-average sea levels are shown in red and white, and below-average sea levels are shown in blue and purple. Source: NASA/JPL-Caltech
A historical review of the El Niño phenomenon
Two extreme El Niño events have occurred in the past 30 years: the first in 1997-1998 and the second in 2015-2016. Both events caused changes in global air and ocean temperatures, atmospheric wind and rainfall patterns, and sea levels. The map above shows sea level in the Pacific Ocean in 1997, 2015 and early October 2023, with red and white representing above-average sea level and blue and purple representing below-average sea level. Michael Freilich's Sentinel-6 captured the 2023 data, the TOPEX/Poseidon satellite collected data for the 1997 image, and Jason-2 collected data for the 2015 map.
By 1997 and October 2015, sea levels were more than 7 inches (18 centimeters) above normal in large areas of the central and eastern Pacific. Compared with conditions in 1997 and 2015, sea levels this year are about 2 or 3 inches (5 to 8 centimeters) higher than average and cover a smaller area. The past two El Niños have peaked in late November or early December, so this year's El Niño is likely to intensify.
"Every El Niño is a little different," said Josh Willis, Sentinel-6 Michael Freilich project scientist at NASA's Jet Propulsion Laboratory (JPL) in Southern California. "This one may seem small compared to big events, but if conditions are right, it could still bring a wet winter to the southwestern United States."
The Michael Freilich Sentinel-6 satellite was launched in November 2020 and was named after Michael Freilich, the former director of NASA’s Earth Science Division. The satellite is one of two satellites part of the Copernicus Sentinel-6/Jason-CS (Continuous Service) mission.
Sentinel-6/Jason-CS was jointly developed by the European Space Agency (ESA), the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT), the National Aeronautics and Space Administration (NASA) and the National Oceanic and Atmospheric Administration (NOAA), with financial support from the European Commission and technical performance support from the French National Center for Space Research (CNES).