J6.2 Redistribution of Saharan Dust in the Vicinity of Tropical Convection

Wednesday, 25 January 2017: 11:00 AM
4C-4 (Washington State Convention Center )
Cynthia H. Twohy, NorthWest Research Associates, Redmond, WA; and R. A. Ferrare, B. E. Anderson, S. C. van den Heever, S. R. Herbener, K. Sauter, and T. S. L'Ecuyer

Over the tropical Atlantic Ocean, storm systems often interact with the dry, dust-laden Saharan Air Layer (SAL). However, the amount of dust that is processed and redistributed by these storms, and its impact on the structure of the SAL layer, is unknown. The lofting and removal of dust by convection has important implications for direct and indirect radiative forcing in both current and changing climates. Initial studies by our group suggest that convective lofting may be an important source of ice nucleating particles to the mid/upper troposphere, as well as providing significant nutrients to the ocean surface and potentially impacting ocean biogeochemistry.

This presentation will focus on airborne lidar and in-situ microphysical data in and around tropical storms over the Atlantic Ocean. Prior analysis showed an enhancement of both large and small particles in the anvil outflow region of storms impacted by the SAL, but the enhancement didn’t extend more than 20 km from the cloud edges at a fixed altitude. For this work, aircraft lidar data will be used to study the vertical structure of aerosol layers near storms. Specifically, we will examine at what levels dust is preferentially redistributed, as well as the relative roles of sedimentation/evaporation of ice crystals in the anvil region and of detrainment at all levels. Ultimately, these data will be combined with satellite data and modeling studies to assess storm impacts on the vertical structure of dust across the Atlantic Ocean.

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