ESA - SMOS Mission logo / NASA - Aquarius Mission patch.
22 April 2013
The saltiness of the oceans is being closely monitored from space by both ESA’s SMOS and NASA’s Aquarius missions, but in slightly different ways. By joining forces, researchers are exploiting these complementary missions to benefit climate science even further.
Freshwater plume from SMOS (top) Aquarius (bottom)
Everyone knows that seawater is salty, but it isn’t that obvious that the concentration of salt – the salinity – of the surface waters of the world’s oceans varies considerably with location and season.
Salinity is controlled largely by the balance between evaporation and precipitation, so it is an important component of Earth’s water cycle and closely coupled to weather and climate. It is also an important driver in ocean circulation, which in turn, is crucial in moderating the climate.
In fact, ocean salinity is an 'essential climate variable' – a key parameter of climate change.
SMOS in orbit
Until the launch of SMOS in 2009 and Aquarius in 2011, global data on this important variable were simply not available. Scientists need this information to feed into the mathematical models they use to understand the complexities of the exchange processes between Earth’s surfaces and the atmosphere.
Thanks to both missions, these much-needed data are leading to a better understanding of the water cycle, how the ocean works and how salinity is linked to weather and climate.
ESA’s SMOS satellite and NASA’s Aquarius sensor, carried on Argentina’s SAC-D satellite, both use an L-band radiometer to map ocean salinity but offer different resolutions and revisit times.
Salinity from SMOS and Aquarius
For example, Aquarius provides better ‘pixel’ accuracy than SMOS, whereas SMOS provides higher revisit times and spatial resolution.
While it has been shown clearly that their datasets agree and provide similar information, the differences in the data can be exploited to yield even more detail about variations in the salinity of our oceans.
Aquarius in orbit
For instance, the animation above shows the freshwater plume in the Pacific Ocean west of Panama as seen from both missions. This fresh pool is a consequence of heavy summer rains over Central America. Wind is also an important factor in the salinity of the water in this region.
Related links:
SMOS: http://www.esa.int/Our_Activities/Observing_the_Earth/SMOS/
Access SMOS data: http://earth.esa.int/SMOS/
Essential climate variable: http://www.wmo.int/pages/prog/gcos/index.php?name=EssentialClimateVariables
SMOS & Aquarius science workshop: http://www.smosaquarius2013.org/
Aquarius: http://aquarius.nasa.gov/index.html
Ifremer: http://www.salinityremotesensing.ifremer.fr/home
SMAP: http://smap.jpl.nasa.gov/
CONAE: http://www.conae.gov.ar/eng/
Images, Video, Text, Credits: ESA / P. Carril / NASA / IFREMER / ESR.
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