| Summary: | Global wind field measurements are essential to improve our knowledge of atmos-pheric dynamics, including atmospheric transport processes of energy, water and airbourne particles. Unfortunately, coverage of wind observations is rather poor over the oceans and the polar regions. Only a few regular wind measurements are made along coastal areas of the Arctic, Antarctica and the interior of Canada, Alaska, Russia and Northern Europe, but there is little or no coverage of the interior of Antarctica, Greenland or the Arctic Ocean. Poor knowledge of the polar wind field is a major cause of larger than normal analysis and forecast errors in these regions, leading to occasional forecast “busts ” in areas like Europe, influenced by synoptic disturbances originating in polar regions. Recently a new satellite-derived wind product, developed at the Cooperative Institute for Meteorological Satellite Studies (CIMSS), has become available, which provides information on polar wind fields. The winds are derived by tracking features in the IR window band at 11 µm and in the water vapour (WV) band at 6.7 µm from the Moderate Resolution Imaging Spectrodiameter (MODIS) instrument on board the polar-orbiting satellites Terra and Aqua. Wind vector heights are assigned by using either the IR windows, CO2 slicing or the H2O intercept method (Key et al., 2002). Results of the NOGAPS model are used as a first guess wind field. MODIS winds are available in areas north of 65o N and 65o S.
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