Evaluation of WRF-ARW Model in Reproducing a Heavy Rainfall Event Over Chalkidiki, Greece: The Effect of Land-Surface Features on Rainfall

Abstract

A record breaking 24 h accumulated rainfall event was observed in Chalkidiki Peninsula, Greece on the 8th of October 2006. Intense precipitation was associated with strong low level convergence imposed by a low pressure system developed over the Aegean Sea and topographical lifting in the area of interest. Severe flooding and damage was reported especially in the east coast of Chalkidiki. The ability of WRF model to simulate this extreme precipitation episode using three different operational microphysical schemes was tested by comparing the high resolution results with available raingauge data. The verification results indicate that WRF configuration using ETA Ferrier microphysics provides better statistical scores for heavy hourly precipitation rates while it was able to reproduce the spatial rainfall distribution of this event. PLIN scheme captures the measured 24 h accumulations especially where maximum precipitation is observed. Sensitivity experiments suggest that highly localized heavy rainfall was the result of an interaction between synoptic conditions and the topographical features, with large scale forcing imposing a low-level convergent flow field that produced heavy rain and topography enhancing highly localized precipitation maxima.