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. Images are published as soon as data is available, typically in the morning. The Arctic data is produced with a delay and is published 1-2 days later.


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 on observations from 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).

Documentation and the data itself can be accessed on the Copernicus Marine webpage. Links are given here for the Arctic data and the North Sea and Baltic Sea data including Denmark. The global data has not been published yet, but is based on similar algorithms as the other two data sets. Feel free to contact us, if more information on the global data is needed.


Anomaly / Climatology

The SST anomalies have been calculated by subtracting the surface temperature 1991-2020 climatological mean. In the Arctic a daily climatology is computed from sea and sea ice surface temperature data from DMI and Copernicus Marine . The global climatology constists of daily mean sea temperatures based on data from Met Office (UK) and Copernicus Marine. Climatological monthly means for the North Sea and Baltic including the sea around Denmark is also based on data from DMI and Copernicus Marine. When using monthly climatologies, the daily climatological temperature 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.


Comments and suggestions

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Danish Meteorological Institute