A 2-year climatology of polar low events over the Nordic Seas from satellite remote sensing

A new 2-year data set of polar low events over the Nordic Seas is presented. The detection of polar lows is based on the combined use of thermal infrared AVHRR imagery and SSM/I derived wind speeds from the satellite climatology HOAPS (Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data). A total of 90 polar lows are found in 2004 and 2005 with a maximum of polar low activity during the winter months. The main polar low genesis regions lie between Iceland and Finnmark in the Norwegian Sea, in the Barents Sea and in the lee region of Cape Farewell. Interannual variability in polar low activity results mostly from more frequent cold air outbreaks in 2004. Statistics for several atmospheric parameters (e. g., wind speed, precipitation, cloud top temperatures) which describe the intensity of the cyclones are retrieved from satellite observations. The data set builds a basis for studies about polar low forcing mechanisms and for the validation of mesoscale numerical models.