Quantitative analysis of Bora events in the Adriatic Sea by means of SAR-based techniques and the ETA model

Bora is the north-eastern wind which, blowing in the Adriatic Sea from NE and interacting with the orography of the Croatian Dinaric Alps, is characterized by multiple surface intense wind jets [1]. The exceptional Bora events of the beginning of February 2012 over the Gulf of Trieste have been studied by means of two ASAR Wide Swath (WS) images, acquired on the 2nd and 5th of February. Two different methods to extract wind direction from SAR images have been exploited to catch the spatial dynamic of this extreme phenomenon. In particular, SAR sea surface wind directions obtained with Local Gradient (LG) method [2] and the relatively novel technique based on the use of 2D continuous wavelet transform (CWT2) [3] have been analyzed. The retrieved wind directions extracted by the above mentioned methods have been used to estimate the wind speeds with a classical inversion procedure applied to the forward semi-empirical backscatter model CMOD-5 [4]. Results will be compared with wind fields simulated by the atmospheric ETA model [5].