Numerical study of a coastal fog event over Casablanca, Morocco

Abstract

This numerical study focuses on a dense fog event that occurred during the night of 21–22 January 2008 in the Grand Casablanca region, on the northwestern coast of Morocco. This fog event, which lasted for 15 h, is simulated by the mesoscale non‐hydrostatic model Meso‐NH and analyzed using conventional meteorological observations from two synoptic stations of the region, Meteosat Second Generation (MSG) satellite imagery and the European Centre for Medium‐Range Weather Forecasts (ECMWF) ERA‐Interim reanalysis. Results demonstrate that this fog event included the formation of radiation fog over a continental zone and its extension to the coastal zone through the lowering of low‐stratus clouds, which is in agreement with observations and is captured well by the Meso‐NH model. Sensitivity experiments show that coastal fog prediction improves with improved sea‐surface temperature. Model skill also depends on the adjustment of microphysical parameters when a single‐moment microphysical scheme is used, and on reliable initial conditions.