The moisture fluxes during wet conditions over the Mediterranean Basin are substantially different from long term moisture fluxes. However moisture fluxes shows similarity during dry and normal conditions over Mediterranean in terms of direction and magnitude. As a result, the large scale atmospheric conditions during the average normal and dry conditions are similar and both Western and Eastern Mediterranean prone to dry conditions. Therefore, it is hard to detect influence of atmospheric and oceanic teleconnections for the larger Mediterranean Basin for dry conditions. The driest Eastern Mediterranean winters were selected according to the Standardized Precipitation Index (SPI) (Figure a,b), and the differences in moisture budget between them and average conditions (i.e. climatology) were investigated (Figure c,d). Then, we calculated the correlation of SPI with Arctic Oscillation Index conditional on driest years. Thus, we were able to obtain the spatial configuration of AO patterns related to driest conditions. This approach gave the opportunity to compare teleconnection patterns which affect driest/wettest conditions over larger Mediterranean basin. According to the results; higher pressure at mid-latitudes because of positive phase of AO changes circulation patterns and cause drier conditions over the Eastern Mediterranean (Figure e,f). The relative strengths and positions of these large-scale systems cause Eastern and Western patterns of the Mediterranean climate variability.
Figure a,b:Geographical distribution patterns of 3-month SPI values calculated for the Eastern Mediterranean Basin for the selected two winters during the period 1949-2010.
Figure c,d:Composite anomalies map of 10 driest January anomalies with respect to the January climatology calculated for a) Western Mediterranean and b) Eastern Mediterranean. Vertically integrated atmospheric moisture flux (AMF) (vectors, in kg•(ms)-1) and AMF convergence (shaded and contours, in mm month-1)