WRF Model and ASAR-retrieved sea surface wind field comparison in a case study over eastern Mediterranean Sea

Synthetic Aperture Radar (SAR) imagery usually detects well the signatures of coherent atmospheric structures, due to the modulation of the sea surface roughness induced primarily by the interaction between the wind flow and the orography and by the spatial structure of the marine atmospheric boundary layer itself. In the present study, the wind field derived from an Envisat Advanced SAR (ASAR) image has been analyzed and compared with those simulated with the Weather and Research Forecasting (WRF) model over an area located in the eastern Mediterranean Sea, southward and eastward of Crete island. This is a region subject to complex wind patterns, due to the interaction of the almost steady northerly Etesian wind with the orography of the islands in the region. The ASAR Wide Swath image analyzed covers an area of about 400 km by 400 km with a spatial resolution of about 150 m by 150 m (pixel of 75 m by 75 m). Thus, the extracted wind field can have an exceptionally high resolution, appropriate for investigating the mesoscale phenomena on the marine atmospheric boundary layer. The ASAR derived wind field has been extracted with a methodology based on the 2-D Continuous Wavelet Transform, suitable to isolate the backscatter patterns on the base of energy and scale considerations. WRF model simulations have been performed using three 2-way nested domains, the inner one covering the area of interest with a resolution of 1 km. Simulations using different diffusion and boundary layer parameterization schemes have been tested in a case study corresponding to mountain lee waves detected in the ASAR image. The 10 m wind fields are compared each other and with those retrieved from the ASAR, both quantitatively and qualitatively, in order to analyze the correspondence of observed and simulated wind structures.