Information


Information about the figures

The web page shows the sea surface temperature (SST) and anomalies derived from infrared measurements from the polar orbiting satellites. One interpolated field is constructed daily. Only nighttime SST observations are used for the interpolation because these are more representative of the temperature in the upper meters of the water column. One image per day is shown for the last 30 days.

The SST anomalies have been calculated with respect to a mean, which has been derived from observations from 1985 to 2001. They are SST climatology monthly values from the Pathfinder project and temporal interpolation is used between the two nearest months to obtain this days SST climatology. For more information on the monthly climatology, see: www.nodc.noaa.gov/sog/pathfinder4km/


Interpolation method

Gaps in the observations due to clouds are filled using a 3-dimensional Optimal Interplation technique (see Høyer and She, 2007). The interpolation scheme uses statistics, which are derived locally and provides the "best possible" estimate of the SST observations, assuming steady state statistics. The mean error of the gridded SSTs is about 0.5-0.7oC.

Satellite observations

The observations of the sea surface temperature are based upon observations from up to 10 different satellites, measuring in Infrared and Microwave wavelengths. The observations are obtained from the Ocean and Sea Ice SAF project (www.osi-saf.org) and from Group on High Resolution Sea Surface Temperature (www.ghrsst.org).
The satellites products are listed below: 

Sensor Satellite Resolution (km)
AATSR
 ENVISAT
 1
AVHRR (OSI-SAF) NOAA 2
AVHRR (NAVO LAC) NOAA 1
AVHRR (NAVO GAC) NOAA 4
AVHRR METOP_A 1
Modis Aqua 1
Modis Terra 1
AMSR-E Aqua 25
TMI TRMM 25
SEVIRI MSG 5
GOES 5


Anomaly / Climatology

The SST anomalies have been calculated by subtracting a SST climatological field, which is based upon the Pathfinder climatology . The Pathfinder project has calculated monthly climatological values from nighttime satellite observations from the period 1985 to 2003. For a given day, the climatological SST field has been calculated by linear interpolation between the monthly SST fields before and after the current day.


References

Høyer, J. L. and She, J., 2007. Optimal interpolation of sea surface temperature for the North Sea and Baltic Sea,  J. Mar. Sys., Vol 65, 1-4, pp. 176-189, 2007. 

Høyer, J. L. and She, J., 2004. Validation of satellite SST products for the North Sea-Baltic Sea region, DMI technical report, 04-11.


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Danish Meteorological Institute