Simulation of Transport and Removal Processes of the Saharan Dust

Abstract

A planetary boundary layer (PBL) model has been modified to include a Saharan air layer containing the bulk of Saharan dust. The Saharan air layer is recognized as a deep mixed layer which extends up to 4?6 km during hot summer months and is characterized by high potential temperature and high dust concentration. Microphysical processes of particle coagulation and sedimentation have been coupled with dynamic processes to simulate the evolution of dust particles. In agreement with observations, simulations indicate that dust particles greater than 10 ?m radius can be produced and transported in the Sahara air layer across the Atlantic ocean, whole dust concentrations in the PBL over the Atlantic Ocean are smaller by a factor of two or more than in the Saharan air layer.