OSI SAF central
Surface radiative flux products
The high latitude radiative flux products developed at the Norwegian Meteorological Institute contains shortwave (SSI) and longwave (DLI) irradiance received at the surface.
The Ocean and sea Ice SAF radiative flux products are currently produced at 5 and 10 km spatial resolution once daily. Input data are AVHRR data from both NOAA POES and Eumetsat Polar System (EPS).
Currently data are delivered in a Polar Stereographic map projection, but work is ongoing to deliver in satellite projection. Although each satellite passage is processed, the official radiative flux products from the EUMETSAT OSISAF are daily products which represents the mean daily irradiance received at the surface in Watt per square meter.
Daily quicklook products are available through the specific product description pages for SSI and DLI respectively. WMO GRIB and HDF5 files including quality flag etc are available for FTP download through the main page. Work is ongoing to deliver data in NetCDF/CF as well as covering the whole area indicated in the illustrations below.
The estimates based on remote sensing data are routinely validated against available in situ measurements. Much effort has been dedicated to validation and gaining access to relevant validation data in recent years. In the sample products provided here and on the individual product pages white circles indicate validation stations where data are available for usage in the OSISAF validation scheme. Not all these are used all the time and some of them only cover shortwave products. Extracts from the validation report will be presented on these pages twice yearly. The normal validation report covers periods of 6 months, but longer validation reports will be provided here soon.
In the illustration provided, the following keywords are used:
The most recent validation results, covering a period of 6 months is presented below. Not all stations listed in the map above is used. For some of the stations, extensive shadow effects cause problems validating SSI, work is ongoing to create adjustment factors for these. The illustration presented here is the relative bias error of the product. The left panel shows validation results for SSI and the right panel for DLI. This ilustration is a merged version of the validation results for several validation periods.
Typically the quality of the SSI products is poorer during winter than during summer due to the snow covered ground at high latitudes. Maintenance of the in situ equipment may also affect results, but usually stations affected by such issues are removed from the validation until they are working properly again (this is why the stations used may differ between validation periods). The quality of DLI is usually slightly poorer during summer than during winter due to more scattered cloud cover.