Sea Surface Winds over the Mediterranean Basin from Satellite Data (2000–04): Meso- and Local-Scale Features on Annual and Seasonal Time Scales

Abstract

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.

The summer circulation over the eastern Mediterranean and the Middle East: influence of the South Asian monsoon

“…1b), known in the Aegean Sea region as the Etesians (HMSO 1962;Metaxas 1977;Maheras 1980;Prezerakos 1984;Reddaway and Bigg 1996;Zecchetto and de Biasio 2007;Chronis et al 2011). The ventilating effect of the Etesians counteracts the adiabatic warming induced by large scale subsidence especially over the central and eastern Mediterranean ), which inhibits cloud formation and convection, resulting in a prolonged summer dry period.…”

Offshore wind climate analysis and variability in the Mediterranean Sea

“…Zonal variations were evident for both wind and wave fields while local zonal maxima were absent for wave fields due to its dispersive nature, in contrast with the wind fields that were well-defined. Zecchetto and De Biasio (2007), denoted hereafter as ZdB (2007), analysed wind data provided by the SeaWinds scatterometer from 2000 to 2004 over the Mediterranean and Black Sea, and presented a quantitative assessment of the spatial distribution, the seasonal wind stress fields and the annual and seasonal vorticity fields. The authors also investigated some important local-scale orographic effects in the Mediterranean, exhibiting a seasonal variability similar to the regional winds.…”

Numerical models sea surface wind compared to scatterometer observations for a single Bora event in the Adriatic Sea

“…Winds fields provided by scatterometers are given for neutral stability conditions. While in the open ocean the stability conditions are close to neutral (Chelton and Freilich, 2005), in the Mediterranean Sea, on average, they range from neutral to unstable (Zecchetto and De Biasio, 2007). The correction of scatterometer winds from neutral to real stability conditions affects mainly low winds, implying a reduction of 20-30 % for unstable conditions and an increase of +20 % for stable conditions in the Mediterranean Sea (Zecchetto and De Biasio, 2007).…”

“…While in the open ocean the stability conditions are close to neutral (Chelton and Freilich, 2005), in the Mediterranean Sea, on average, they range from neutral to unstable (Zecchetto and De Biasio, 2007). The correction of scatterometer winds from neutral to real stability conditions affects mainly low winds, implying a reduction of 20-30 % for unstable conditions and an increase of +20 % for stable conditions in the Mediterranean Sea (Zecchetto and De Biasio, 2007). To compare scatterometer data with model winds, the adjustment can be done in two ways: modifying the scatterometer values to real stability conditions, or viceversa, adjusting model winds to neutral stability.…”