Analysis of the Representation of the Vertical Structure of the Saharan Air Layer over Northern Africa and the Eastern Atlantic Using MERRA-2

The Saharan air layer (SAL) is a warm, dry, and dusty isentropic layer that results from the intense surface heating and dry convection over the Saharan Desert. Previous studies often consider the radiative and microphysical impacts of dust aerosols on weather systems and deep convection independently, yet both dust-related impacts occur concurrently and at times in opposition. Toward this research goal, our objective in this presentation is to characterize the structure of the SAL as represented in the NASA Modern Era Retrospective-analysis for Research and Applications (MERRA-2) global analyses with the Goddard Chemistry Aerosol Radiation and Transport (GOCART) at 0.5°x0.625° grid resolution. We will investigate the capabilities of MERRA-2 to reproduce observed thermodynamic and aerosol structures as compared to available rawinsondes, Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth (AOD), and NASA airborne data sets. Accurate representation of the SAL in models is important because it shapes the energetics of African easterly waves and potentially downstream tropical cyclone development. We will also present the seasonal structure and evolution of Saharan dust and its thermodynamic properties as revealed by examining the MERRA-2 global analyses.