Sensors measuring emitted
radiation in the infrared part of the electromagnetic spectrum can be
used to derive the temperature of the surface of the Earth. GRAS has
many years of experience in operational systems deriving the Sea Surface
Temperature. From our own HRPT satellite receiving station GRAS can
deliver operational SST data from NOAA AVHRR covering Northern Europe
within 30 min of acquisition. From processing chains based on MODIS
Aqua/Terra and GOES GRAS can deliver worldwide coverage of SST data
within a few hours after reception.
The illustration below shows a NOAA AVHRR time series of the inner
Danish waters during the summer month of August. Time series of Sea
Surface Temperature is very useful for identification of currents,
fronts and to provide an overview of the general circulation patterns of
a particular area
The processing system at GRAS
incorporates auto-correlation routines to automatically geo-reference
the data to within subpixel accuracy. If needed, an automatic cloud mask
can also be applied.
The accuracy of the Sea Surface Temperature maps from NOAA AVHRR data
is approximately 0.5 °C and similar accuracies are found from the MODIS
and GOES products. The standard spatial resolution of the Sea Surface
Temperature maps is 1000 meters.
Sea Surface Temperature can be used for a wide range of applications
e.g. location of fronts and currents, assimilation and validation of
oceanographic models, meteorological modelling and temporal analysis of
Sea Surface Temperature for global change studies.
As an example of the worldwide coverage
GRAS is maintaining an operational delivery of SST data covering the
Gulf of Mexico. Daily composite images are used as input to forecast
modelling and are automatically processed and transferred to the client
via ftp.