ESA: SMOS satellite measurements improved

Radio frequency interference (RFI) at northern latitudes in February 2011 and February 2012 seen as red dots.
Picture: ESA

Over a dozen radio signals that have hindered data collection on ESA’s SMOS water mission have been switched off. ESA’s Soil Moisture and Ocean salinity (SMOS) satellite was launched in 2009 to improve our understanding of our planet’s water cycle. In order to do this, it measures the microwaves emitted by Earth in the 1400–1427 MHz range. Radio signals in this frequency range render some of its measurements unusable for scientific purposes. With the support of national authorities, ESA was able to pinpoint the origin of these unlawful emissions.

At least 13 sources of interference have now been switched off. This has significantly improved SMOS observations at high latitudes, which were previously so contaminated that accurate salinity measurements were not possible above 45 degrees latitude as the satellite headed north. One of the largest areas of contamination in the northern hemisphere is over the North Pacific and Atlantic oceans, primarily from military radars. The efforts to reduce interference will benefit other missions carrying similar detectors, such as NASA’s Aquarius satellite, which was launched last year and which measures ocean salinity at the same frequency.