PERFORMANCE OF 2 CUMULUS CONVECTION PARAMETERIZATIONS FOR 2 HEAVY PRECIPITATION EVENTS IN THE WESTERN MEDITERRANEAN

A set of mesoscale numerical simulations using the Emanuel and Kain-Fr itsch deep convection schemes has been performed in order to determine the sensitivity of the forecast - especially, the rainfall - to the s cheme used. The study is carried out for two cases of heavy precipitat ion in the coastal zone of the Western Mediterranean, where the topogr aphic forcing is of primary influence. The first one, characterized by an almost stationary synoptic situation, is dominated by warm, moist advection at low levels; the second one, of frontal type, presents a m uch stronger dynamic forcing at upper levels. Although the comparison attempt is conditioned by the limited number of considered cases, the numerical results provide at least some preliminary conclusions. The i nclusion of a convective scheme improves the forecast precipitation, t hrough two actions: directly, producing more realistic rainfall patter ns in areas of convection; indirectly avoiding excessive precipitation in areas with orographic or dynamical upward forcing by drying and st abilizing the atmosphere upstream. In particular, the Kain-Fritsch sch eme seems to be more sensitive to the orographic forcing, in agreement with observations.