The effect of the island of Crete on the Etesian winds over the Aegean Sea

The Etesians (northern sector winds), which blow over the Aegean Sea during summer, affect human activities in the area. The numerous islands of the A egean and especially Crete (a mountainous island in the southern Aegean ori ented perpendicular to the surface flow) seem to play an important role in the modification of the wind field during the Etesians. The Crete mountain ranges, surrounded as they are by water, are an excellent example of a majo r isolated topographic feature which significantly modifies the regional ai rflow and pressure; however, this modification can hardly be defined due to the lack of observing stations over the sea. For this reason, the availabl e land surface and ship synoptic observations are used, together with ERS s catterometer wind data in order to identify the regions over the Aegean whe re the wind reaches its maximum intensity, and to assess the influence of C rete on the wind field. Moreover, numerical modelling is used to provide so me further insight on the orographically disturbed wind flow, Sensitivity t ests performed with the hydrostatic model BOLAM show that the interaction o f the Etesian wind flow with the mountains of Crete produces deceleration o f the Etesians up to almost 120 km upstream, the leftward deflection of the air as it approaches the mountains, and the associated intensification of the flow east of the island.