Global Aspects Of Orographic Precipitation

Abstract:

Orographic precipitation around the world is particularly important for water resources as it determines the discharge in the most of world’s rivers. Current climate models do not resolve the physical processes that control orographic precipitation. Over the last three decades, several field projects have studied orographic precipitation in mid-latitudes. Recently, a tropical field project has been completed (i.e. DOMEX). Based on all these results, we are now in a position to compare and classify mountain ranges in different climate zones on the basis of the controlling environmental parameters: water vapor flux statistics, blocking and deflection, role of convection and melting level. Using these factors, we have studied 68 representative mountain ranges around the world; categorizing them into classes with similar physical characteristics. We also compare conventional and stable isotope measures of mountain drying ratio. We consider what advances must occur before GCMs can give accurate predictions of orographic precipitation