Title_575

This study represents the first large-scale systematic dendroclimatic sampling focused on developing chronologies from different species in the eastern Mediterranean region. Six reconstructions were developed from chronologies ranging in length from 115years to 600years. The first reconstruction (18852000) was derived from principal components (PCs) of 36 combined chronologies. The remaining five, 18002000, 17002000, 16002000, 15002000 and 14002000 were developed from PCs of 32, 18, 14, 9, and 7 chronologies, respectively. Calibration and verification statistics for the period 19312000 show good levels of skill for all reconstructions. The longest period of consecutive dry years, defined as those with less than 90% of the mean of the observed MayAugust precipitation, was 5years (15911595) and occurred only once during the last 600years. The longest reconstructed wet period was 5years (16011605 and 17511755). No long term trends were found in MayAugust precipitation during the last few centuries. Regression maps are used to identify the influence of large-scale atmospheric circulation on regional precipitation. In general, tree-ring indices are influenced by MayAugust precipitation, which is driven by anomalous below (above) normal pressure at all atmospheric levels and by convection (subsidence) and small pressure gradients at sea level. These atmospheric conditions also control the anomaly surface air temperature distribution which indicates below (above) normal values in the southern regions and warmer (cooler) conditions north of around 40N. A compositing technique is used to extract information on large-scale climate signals from extreme wet and dry summers for the second half of the twentieth century and an independent reconstruction over the last 237years. Similar main modes of atmospheric patterns and surface air temperature distribution related to extreme dry and wet summers were identified both for the most recent 50years and the last 237years. Except for the last few decades, running correlation analyses between the major European-scale circulation patterns and eastern Mediteranean summer precipitation over the last 237years are non-stationary and insignificant, suggesting that local and/or sub-regional geographic factors and processes are important influences on tree-ring variability over the last few centuries.