Circulation and extreme rainfall conditions in the eastern mediterranean during the last century

Dry and wet years, seasons, and sequences at four eastern Mediterranean stations, Thessaloniki, Athens, Nicosia, and Jerusalem, were identified and compared for circulation types. The definition of dry/wet year or season was done by means of z scores. A year or a season was defined as dry when z ≤ - 0.5 and as extremely dry when z ≤ - 1.5, similarly as wet when z ≥ 0.5 and as extremely wet when z ≥ 1.5. Dry/wet sequences at each station were identified and their timings were compared. Circulation types were defined by means of zonal and meridional indices calculated independently in two regions. Region 1 : Φ = 35°N and 55°N; λ = 10°E and 30°E for Thessaloniki and Athens. Region 2: Φ = 30°N and 50°N; λ = 20°E and 40°E for Nicosia and Jerusalem. Time series of both indices in both regions were calculated and are discussed. Correlations between the z scores of the precipitation with both indices were calculated. Prevailing flows for dry and wet conditions for each of the stations were defined and are discussed.