The Influence of Tropical Convection on the Evolution and Transport of the Saharan Air Layer

Over the tropical Atlantic Ocean, storm systems often interact with the dry, dust-laden Saharan Air Layer (SAL). Prior studies have shown that the dust particles and associated dry air within the SAL impact tropical convection in multiple ways. In addition to researching impacts of the dust layer on convective storms, we are studying the converse: how convection impacts the temporal and spatial distributions of dust through cloud processing and transport. With a unique combination of aircraft and satellite data sets and regional cloud modeling, the amount of dust transferred from the atmosphere to the Atlantic ocean through convective precipitation is being assessed. These same integrated tools are being used to determine whether substantial dust is transferred vertically and horizontally in the atmosphere through convective venting. The removal and redistribution of dust by convection has important implications for direct and indirect radiative forcing in both current and changing climates, as well as potentially impacting ocean biogeochemistry.

This paper will focus on both aircraft and satellite measurements where convection interacts with dust over the Atlantic. Aircraft lidar and in-situ microphysical data in and around tropical storms will be used to examine changes in the SAL profiles near convection. The potential lofting of dust particles to the mid and upper troposphere, where they may participate in cirrus cloud formation, will be assessed. In addition, composite CALIPSO and GOES East Pathfinder Atmospheres Extended (PATMOS-x) satellite datasets will be used to examine changes in the SAL layer after interaction with convection. Ultimate goals of this work include establishing storm impacts on the vertical structure of dust across the Atlantic Ocean and quantifying the amount of dust removed to the oceans by precipitation associated with deep convection.