Atmospheric boundary layer rolls near Spitsbergen studied by ERS SAR and a numerical model

Abstract

Sea surface manifestations of atmospheric boundary layer rolls visible on ERS-1 SAR image acquired on March 24, 1993, over the Greenland Sea near Spitsbergen during a cold air outbreak are analysed. The variation of the spacing between the roll axes as a function of distance from the ice edge is determined from the ERS SAR image. Furthermore, the variation of the wind speed at the sea surface caused by the air flow associated with the boundary layer rolls is inferred from the SAR image by using the CMOD4 wind scatterometer model. Quasi-simultaneously with the ERS SAR image aquisition in-situ meteorological measurements were carried out from a research aircraft. These meteorological data are used in a three-dimensional mesoscale atmospheric model by which the formation of the atmospheric boundary layer rolls is simulated. This model can explain the observed variation of the aspect ratio, i.e., the ratio between the spacing of the roll axes and the height of the boundary layer as a function of distance from the ice edge. The comparison of the sea surface wind speeds calculated from the model and inferred from the ERS-1 SAR image shows a reasonable agreement .
Keywords: synthetic aperture radar, atmospheric phenomena, boundary layer rolls, cold air outbreak

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry