The wind and wave atlas of the Mediterranean Sea - the calibration phase

Abstract. Within the WW-Medatlas project, sponsored by the Italian, French and Greek Navies, an extensive atlas of the wind and wave conditions in the Mediterranean Sea has been completed. The atlas is based on the information derived from the archive of the European Centre for Medium-Range Weather Forecasts, UK, then calibrated on the base of the data available from the ERS1-2 and Topex satellites. The calibration is required because the wind, hence the wave, data are normally strongly underestimated in the enclosed seas. The calibration has been done deriving the model values at each satellite position, typically at 7 km intervals. The co-located values have then been assigned to the closest grid point. This has provided a substantial number of couples of data at each point, then used to derive, by best-fitting technique, the correction required. This turns out to vary amply throughout the basin, according to the local geometry and orography. The calibration coefficients, different for wind and waves, have been used to correct the original fields and the time series at the single points. Using the calibrated data, extensive statistics have been derived, both as fields and at each point, including extreme values.