Interactions Between Saharan Dust and Tropical Convection

The Saharan Air Layer has been observed to influence hurricane development over the tropical Atlantic Ocean, and Saharan dust particles have been found within cirrus anvil crystals over the eastern and western Atlantic. However, interactions between dust layers and the microphysical and dynamic properties of tropical clouds are not well understood. While dust particles are known to act strongly as heterogeneous ice nuclei, they also can adsorb and absorb water and can act as cloud condensation nuclei. Potentially different effects of dust on convection are possible depending on the nucleating mode (droplet vs. ice). Additionally, tropical storms may influence the distribution and loading of dust within the atmosphere, with impacts on climate and ocean biogeochemistry. We studied interactions between Saharan dust and tropical convective systems, using airborne measurements and an improved version of the RAMS cloud-resolving model. Simulations of small storms and tropical cyclones were initialized with actual field data from the NAMMA field program. Tracking of dust mass throughout the storm was also implemented, so the location of dust and how much was removed through precipitation could be assessed. Results are discussed in relation to field measurements of dust in the anvil region, as well as tropical storm development and evolution.