Measuring the Rising Seas
 
Jan. 26, 2016:  Earth is enveloped by a vast ocean that covers about 71
percent of our planet. Even tiny changes in this body of water can add up to
enormous effects on climate and weather.
 
The Jason-3 satellite, launched on January 17, 2016, will allow scientists to
continue a 23-year record aimed at studying Earth's ocean to better understand
and forecast our climate, months and years into the future.
 
Jason-3 project scientist Josh Willis of NASA's Jet Propulsion Laboratory in
Pasadena, California says, "Jason-3 will measure the rising oceans and
changing climate for the next five years."
 
 
Jason-3 is the latest in a series of satellites that accurately measure the
height of the ocean surface dating back to the launch of Topex/Poseidon in
1992. Next came Jason-1 (launched in 2001) and then Jason-2 (launched in
2008). Jason-3 will be joining Jason-2 in orbit. For Jason-2 and Jason-3, the
National Oceanic and Atmospheric Administration, or NOAA, and the European
Organisation for the Exploration of Meteorological Satellites, or EUMETSAT
joined an international partnership with NASA and the French space agency,
CNES.
 
Willis adds that "from one mission to the next, we want to overlap our Jason
data and stitch it together to give us a consistent story of how our climate
is warming and our oceans are changing. Global sea level rise measured by
these satellites is one of the clearest indicators of how humans are changing
the climate."
 
This line of data-collecting ancestors have all measured sea surface height
using a radar altimeter -- an instrument similar to weather radars here on
Earth.
 
Here's how it works: The satellite emits a pulse of radar waves that travel
down toward Earth, bounce off the surface of the water, and return toward
space. Once the satellite detects the return signal, the altimeter calculates
the round-trip travel time. The longer the round trip, the lower the waters
are below. The height of the water also tells us about how warm the waters may
be between the surface and the bottom, because warm water expands and causes a
rise in sea surface height. The opposite is true for colder waters.
 
Ocean temperatures are making big news right now as a massive band of warm
water builds up and moves from west to east across the equatorial Pacific
Ocean.  This phenomenon, called "El Ni¤o," causes abnormal weather patterns
around the globe. Ripple effects could include rainy and cooler weather in the
southern United States and a chance to put a dent in California's current
drought. A reverse of the El Ni¤o phenomenon, called La Ni¤a, is associated
with the drought in the Southwest.
 
Willis says, "El Ni¤o is here. We have launched Jason-3 right into the biggest
El Ni¤o since the turn of the millennium, and the Jason data will allow us to
see whether it goes quietly or slingshots the Pacific into a huge La Ni¤a,
like the last big one in 1998."
 
The Topex/Poseidon and Jason satellites have a history of measuring climate
change and monitoring El Ni¤o.  Soon, Jason-3 could be making history of its
own.
 
For updates from the Pacific and around the world, stay tuned to
science.nasa.gov.
 
 
Regards,
 
Roger

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