Interaction of topography and tropospheric flow — A possible generator for the Red Sea Trough?

Summary Numerical investigation of the nature of one of the most typical Eastern Mediterranean atmospheric circulation phenomena — the Red Sea Trough is undertaken. The role of interaction of typical atmospheric flow systems with the local topography of the North African region is analyzed with the help of idealized numerical simulations employing the Penn State and the National Center for Atmospheric Research (NCAR) MM4 modeling system. The simulations are designed, based on results of a climatological evaluation of the 250 hPa wind field. Idealized initial data sets corresponding to typical transient and winter period positions of the upper tropospheric westerly jet stream are constructed. The data for the analysis are from the National Center for Environmental Prediction (NCEP) 25 y (1965–1989) objective analysis archive. It was found that the primary factor in the Red Sea trough generation is the interaction of the mid-tropospheric westerlies with the terrain in the area of the Red Sea.With 5 Figures