Kelvin waves, a potential precursor
of El Niño conditions in the ocean, are rolling across the equatorial Pacific
toward the coast of South America.
The most recent sea level data from
the U.S.-European satellite Sentinel-6 Michael
Freilich indicates
early signs of a developing El Niño across the equatorial Pacific Ocean. The
data shows Kelvin waves – which are roughly 2 to 4 inches (5 to 10 centimeters)
high at the ocean surface and hundreds of miles wide – moving from west to east
along the equator toward the west coast of South America.
When they form at the equator,
Kelvin waves bring warm water, which is associated with higher sea levels, from
the western Pacific to the eastern Pacific. A series of Kelvin waves starting
in spring is a well-known precursor to an El Niño, a periodic climate
phenomenon that can affect weather patterns around the world. It is
characterized by higher sea levels and warmer-than-average ocean temperatures
along the western coasts of the Americas.
Water expands as it
warms, so sea
levels tend to be higher in places with warmer water. El Niño is also
associated with a weakening of the trade winds. The condition can bring cooler,
wetter conditions to the U.S. Southwest and drought to countries in the western
Pacific, such as Indonesia and Australia.
Sea level data from the Sentinel-6 Michael Freilich satellite on April 24 shows relatively higher (shown in red and white) and warmer ocean water at the equator and the west coast of South America. Water expands as it warms, so sea levels tend to be higher in places with warmer water. Credits: NASA/JPL-Caltech
The Sentinel-6 Michael Freilich
satellite data shown here covers the period between the beginning of March and
the end of April 2023. By April 24, Kelvin waves had piled up warmer water and
higher sea levels (shown in red and white) off the coasts of Peru, Ecuador, and
Colombia. Satellites like Sentinel-6 Michael Freilich can detect Kelvin waves
with a radar altimeter, which uses microwave signals to measure the height of
the ocean’s surface. When an altimeter passes over areas that are warmer than
others, the data will show higher sea levels.
“We’ll be watching this El Niño
like a hawk,” said Josh Willis, Sentinel-6 Michael Freilich project scientist
at NASA’s Jet Propulsion Laboratory in Southern California. “If it’s a big one,
the globe will see record warming, but here in the Southwest U.S. we could be
looking at another wet winter, right on the heels of the soaking we got last
winter.”
Both the U.S. National Oceanic and
Atmospheric Administration (NOAA) and the World Meteorological Organization
have recently reported increased chances that El Niño will develop by the end
of the summer. Continued monitoring of ocean conditions in the Pacific by
instruments and satellites such as Sentinel-6 Michael Freilich should help to
clarify in the coming months how strong it could become.
“When we measure sea level from
space using satellite altimeters, we know not only the shape and height of
water, but also its movement, like Kelvin and other waves,” said Nadya
Vinogradova Shiffer, NASA program scientist and manager for Sentinel-6 Michael
Freilich in Washington. “Ocean waves slosh heat around the planet, bringing
heat and moisture to our coasts and changing our weather.”
More About the Mission
Sentinel-6 Michael Freilich, named
after former NASA Earth Science Division Director Michael Freilich, is one of
two satellites that compose the Copernicus Sentinel-6/Jason-CS (Continuity of
Service) mission.
Sentinel-6/Jason-CS was jointly
developed by ESA (European Space Agency), the European Organisation for the
Exploitation of Meteorological Satellites (EUMETSAT), NASA, and NOAA, with
funding support from the European Commission and technical support on
performance from the French space agency CNES (Centre National d’Études
Spatiales). Spacecraft monitoring and control, as well as the processing of all
the altimeter science data, is carried out by EUMETSAT on behalf of the
European Union’s Copernicus programme, with the support of all partner agencies.
JPL, a division of Caltech in
Pasadena, contributed three science instruments for each Sentinel-6 satellite:
the Advanced Microwave Radiometer, the Global Navigation Satellite
System - Radio Occultation,
and the Laser Retroreflector Array. NASA also contributed launch
services, ground systems supporting operation of the NASA science instruments,
the science data processors for two of these instruments, and support for the
U.S. members of the international Ocean Surface Topography Science Team.
To learn more about Sentinel-6
Michael Freilich, visit: https://www.nasa.gov/sentinel-6
Source: International Sea Level Satellite Spots Early Signs of El Niño | NASA
No comments:
Post a Comment