Mediterranean depression characteristics related to precipitation occurrence in Crete, Greece

The characteristics of the cyclone tracks and circulation patterns that caused precipitation events of variable intensity for the period 1979–2011 over the island of Crete are presented. The dataset usedfor cyclone identification, is the 0.5 x 0.5, 30 years European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim mean sea-level pressure. Their characteristics are extracted with the aid of Melbourne University algorithm (MS scheme). Daily precipitation data from a dense gauging network over the island of Crete is also used for the classification of the precipitation events in terms of intensity. Daily precipitation intensity is classified in three severity categories, and the associated cyclones are filtered according to their distance from Crete Island. The atmospheric systems are further investigated both seasonally and annually for their position relative to Crete and morphological characteristics such as intensity and radius. Generally, it was found that cyclones affecting Crete most frequently approach from northwest and southwest directions and the actual cyclone centers associated with precipitation events are usually located in northwest and southeast positions relative to Crete domain. Precipitation increase is observed in parallel with cyclone pressure decrease as well as cyclone intensity, depth, radius and propagation velocity increase. Specific seasonal characteristics such as lower pressures and cyclone radius can be detected in spring in contrast to winter and autumn precipitation events. The examination of the relation between cyclone characteristics and precipitation occurrence provides improved understanding of the complex hydro-meteorological conditions and therefore valuable hydrologic information related to forecasting potential and management of the resources and the extremes.