July 12, 2012

Satellite Thermometers Helping Science

Lee Rannals for - Your Universe Online

There are satellites for nearly everything out in orbit now-a-days, including some that are meant just to provide measurements of the surface temperature of oceans and seas.

These thermometers in the sky led to the meeting of scientists to review data from new satellite missions and scientific progress in the field.

The European Space Agency said that measuring the sea-surface temperature (SST) across regional and global scales is important for improving weather and ocean forecasting and climate change research.

ESA's Medspiration project merges SST maps using data from infrared and passive microwave satellite instruments to map SST dynamics in the Mediterranean. The website uses Medspiration SST maps in its near-realtime service for scientists as well.

ESA began monitoring SST in 1991 by launching the first European Remote Sensing satellite (ERS-1), which carried the Along Track Scanning Radiometer (ATSR).

The space agency launched the Envisat satellite in 2002, helping to ensure continuity of SST measurements with its Advanced Along Track Scanning Radiometer (AATSR).

The radiometers on ERS and Envisat were unique because they use two views of the same sea surface when measuring its temperature.

ESA lost contact with the Envisat back on April 8 this year, ending the spacecraft's 10-year-long mission.

Data from Envisat's AATSR allowed the U.K. Met Office to upgrade the performance of its OSTIA SST analysis system significantly in 2007, ESA said.

“AATSR, with its dual-view capability, was used as a reference sensor and its loss has degraded the accuracy of the OSTIA SST analysis used by weather and ocean modelling systems,” Jonah Roberts-Jones of the Met Office said in a press release.

ESA said its next mission to continue the dual-view SST dataset is Sentinel-3, which is being developed under Europe's Global Monitoring and Environmental Security (GMES) program.

The Sentinel-3 will launch in April 2014, and its Sea and Land Surface Temperature Radiometer (SLSTR) extends the capability of AATSR, having a wider swath and more channels.

“Users need records of SST from space lasting decades, without gaps — and many want the records to be independent of in situ measurements,” Chris Merchant, Science Leader of ESA´s Climate Change Initiative project on SST, said in a press release. “That was achieved with the ERS and Envisat radiometers. It´s important to carry this forward to Sentinel-3.”

Future SST measurements came into focus last month at the 13th Science Team Meeting of the Group for High Resolution Sea Surface Temperature (GHRSST), according to ESA.

The meeting brought international scientists and space agency representatives that maintain the provision of SST data for science and operational services.

The meeting in Tokyo was particularly important as it was the first after the launches of the US satellite Suomi-NPP and the Japanese satellite GCOM-W1,” Prof. Peter Minnett, Chair of the GHRSST Science Team, said in a press release. “Both carry new sensors for the measurement of SST, and so herald a new era of satellite SST research and operational applications."

“Now we look forward to the launch of ESA´s Sentinel-3 to complete the suite of new sensors and continue the multi-decadal time series of SST measurements into the future.”