This paper investigates the mean spatial features of the winds in the Mediterranean and Black Seas using the wind fields observed by the SeaWinds scatterometer. Five years (2000-04) of data have been analyzed on annual and seasonal basis, with particular attention paid to the meso-and local scales. The fields show the existence of structured regional wind systems-in particular, the mistral in the western Mediterranean and the etesians in the Levantine Basin, which are characterized, respectively, by high wind variability and moderate steadiness and by low wind variability and high steadiness. Estimated seasonal mean wind stress fields show that the values falling in the top range 0.15 Ͻ Ͻ 0.20 N m Ϫ2 affect a large portion of the Mediterranean Basin in winter, in the belt extending from the Gulf of Lion up to the Levantine Basin and the northern Black Sea. In the other seasons, only few regions experience such high values of . The analysis of the wind vorticity shows and quantifies the main cyclonic and anticyclonic circulations, and the study of the joint features of wind stress and vorticity has identified the strongest and most persisting local-scale wind circulations produced by the interaction between the wind flow and the orography. They occur at the lee side of Sardinia-Corse and Crete-Rhodos Islands and persist in all seasons, with some seasonal variation in strength and extent. The areas affected by the orographic disturbances are characterized by high values of wind stress and by a structure of vorticity showing alternating areas of cyclonic and anticyclonic circulations, whose strength is comparable to those of the regional-scale cyclones.

Surface wind forecasts from a limited-area model [the Quadrics Bologna Limited-Area Model (QBOLAM)] covering the entire Mediterranean area at 0.1° grid spacing are verified against Quick Scatterometer (QuikSCAT) wind observations. Only forecasts within the first 24 h in coincidence with satellite overpasses are used. Two years of data, from 1 October 2000 to 31 October 2002, have been considered, allowing for an adequate statistical assessment under different wind conditions. This has been carried out by analyzing the fields of the mean wind vectors, wind speed bias, correlation, difference standard deviation, steadiness, gustiness, and mean wind direction difference, in order to investigate spatial variability. Statistics have been computed on a seasonal basis. A comparison of satellite and forecast winds with measurements from three buoys was also performed. Some critical areas of the Mediterranean Sea where wind forecast quality is lower than average have been identified. Such areas correspond to semienclosed basins surrounded by important orography and to small regions at the lee side of the main islands. In open-sea regions the model underestimates wind strength from about 0.5 m s−1 in spring and summer to 1.0 m s−1 in winter, as evidenced by the existing biases against scatterometer data. Also, a wind direction bias (scatterometer minus model) generally between 5° and 15° exists. A survey of the identified and likely sources of forecast error is performed, indicating that orography representation plays an important role. Numerical damping is identified as a likely factor reducing forecast wind strength. The need for a correction scheme is envisaged to provide more accurate forcing for numerical sea state forecasting models, wind energy evaluation, and latent and/or sensible heat exchanges.

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This paper describes a series of wave measurements, taken from an oceanographic tower, concerning water particle kinematics. Attention is focused on the phase relationship between surface elevation and the velocity components. Large phase shifts with respect to the expected values are found under active wave conditions, while swell behavior closely follows the linear theory. The reliability of the measurements is analyzed in detail. Possible physical reasons for the findings are indicated in the final discussion.