ANALYSIS OF MESOSCALE PATTERNS IN RELATION TO SYNOPTIC CONDITIONS OVER AN URBAN MEDITERRANEAN BASIN

In this study day by day synoptic conditions are classified over the A ttica peninsula for a period of sixteen years. Eight synoptic categori es which are demonstrated to be statistically distinct are selected wi th respect to the atmospheric circulation in the lower troposphere. Fu rthermore, a methodology is proposed to classify the mesoscale pattern s for the same period on the basis of surface wind measurements, and t his distinguishes eleven distinct mesoscale categories. In general, th e frequency analysis reveals that the anticyclonic circulation dominat es while the weak mesoscale flows prevail, with preference in May and June. A day by day cross tabulation of the synoptic flow patterns with the mesoscale categories is then performed in order to identify the a ssociation of the synoptic conditions with the mesoscale flow regime. It was found that the synoptic conditions at the level of 850 hPa are closely related to the observed surface local flows and therefore it i s suggested that the synoptic categories can be used for the identific ation of the most favourable mesoscale atmospheric circulation.