Comparison between QuikSCAT and buoy wind data in the Ligurian Sea

Wind above sea surface plays an important role in the Mediterranean Sea for a large variety of scientific applications (i.e., climatological, meteorological and oceanographic studies). In this work we compare wind vectors obtained from the SeaWinds scatterometer on board the National Aeronautics and Space Administration (NASA) QuikSCAT satellite with wind data measured in situ by an anemometer mounted on the offshore ODAS Italia 1 buoy. This platform is moored in the Central Ligurian Sea, a basin where the wind field is highly variable both in time and space due to the orographic constraints and the thermal contrast between land and sea that give rise to specific local effects. The work covers the period from July 2006 to June 2007. The comparison confirms that the QuikSCAT wind vectors satisfy the accuracy requirements for high wind speeds, but, QuikSCAT skill is less for low wind speed, especially for the direction assessment. These results are in agreement with those of previous investigations but the analysis evidences some issues mistreated until now. The most relevant is the scarceness of data. The satellite passes over the Ligurian Sea only twice a day and data taken under rainy condition and with wind speed lower than 3 ms(-1) are not valid. Thus, the temporal sampling may be not adequate to monitor wind fields and their evolution over this basin where calm condition often occurs and strong perturbations are generally associated to rain. Furthermore, the comparison shows that it may be difficult to recognize spurious values obtained from QuikSCAT when the true wind speed is lower than 3 ms(-1) without a reference at sea.