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Abstract: The Arctic Oscillation (AO) has been found in previous studies to be a major synoptic factor affecting the climate of many regions in the high and mid-latitudes. This paper demonstrates the physical process by which the AO affects the climate of the Eastern Mediterranean basin, with a focus on precipitation in Israel as a case study. It is shown that a trend of increasing AO is associated with a substantial decrease of winter precipitation from the Iberian Peninsula, though Italy, Greece, Turkey and Cyprus, as well as Lebanon, Syria and also the northern parts of Israel. Winter rain is slightly increased in the southern coast of the eastern half of the Mediterranean Sea. The immediate meteorological causes are shown to be a larger northerly component of the flow over the Mediterranean Sea, associated with a decreasing relative humidity and stability, except over the southern coast, where the air mass has the longest track over the relatively warm water. We suggest here that the observed changes in air flow that drives the precipitation trends can be explained by shifts in the AO that can be partially explained by increasing greenhouses gases. Results from the IPCC multi climate models show that the AO will continue to increase during the 21st century. This increase may lead to a continuation of the trends discussed here. The importance of the analysis provided here is in pointing out the possibility that processes that have been predicted by global warming and changes in global circulation have already started to affect precipitation and major water resources in the Mediterranean basin. [Copyright &y& Elsevier]

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 τ fields show that the values falling in the top range 0.15 < τ < 0.20 N m-2 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 τ. 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. [ABSTRACT FROM AUTHOR]

Seven years of combined maps of TOPEX/Poseidon (T/P) and ERS-1/2 altimeter data are used to describe the surface circulation variability in the Mediterranean Sea. As described in the past, the Mediterranean Sea level variability is a complex combination of a wide range of spatial and temporal scales. However, this paper gives an improved estimation of sea level statistics (rms, annual, semiannual cycle). Moreover, the longer period (1993–1999) and the merging of T/P and ERS-1/2 altimeter data allows us to observe with a good accuracy the major changes that occurred in the Mediterranean Sea and, in particular, at basin and sub-basin scales. First, important interannual signals were found in the Ionian basin where the cyclonic circulation has clearly intensified since 1997. In the Levantine basin, although the Ierapetra eddy exhibits a clear seasonal cycle, it is not always present during our period of observation.These interannual changes seem to be correlated with the variability of the Mid-Mediterranean Jet, which produces strong meanders. A new view of the circulation in the south of the basin is indeed suggested by considering that the eddies observed in the Mersa-Matruh and Shikmona areas represent meanders of the Mid-Mediterranean Jet rather than permanent structures as commonly described. Secondly, the seasonal cycle of the Alboran gyres is confirmed. Moreover, these gyres and the Ierapetra eddy constitute the most intense signals of the Mediterranean Sea variability. Finally, this descriptive study illustrates the need to continue monitoring the surface circulation in order to better understand the dynamics of the Mediterranean Sea. [Copyright &y& Elsevier]