2.5 The Influence of Tropical Convection on the Transport and Removal of Saharan Dust

Monday, 15 August 2016: 2:30 PM
Madison Ballroom CD (Monona Terrace Community and Convention Center)
Kathryn Sauter, Univ. of Wisconsin , Madison, WI; and T. S. L'Ecuyer

The distribution of mineral dust aerosols that originate from the Saharan Desert and sweep across the tropical Atlantic Ocean can significantly impact climate processes in the region. Dust loadings have been estimated to double in the 20th century, enhancing the impacts of these processes, enhancing their impacts, particularly during drought events (Mahowald et al., 2010, Prospero and Lamb, 2003). The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission was launched in April 2006 as a part of the A-Train constellation in order to gain a better understanding of the role that aerosols and clouds play in the complex climate system [Winker et al., 2006, 2007]. The ability to assess the vertical and spatial transport of dust across the Atlantic Ocean using CALIPSO aerosol retrievals provides valuable insight into the effects of dust aerosols on the Earth's climate system. This study couples in-situ observations of dust storm events with aerosol optical depth from the polar orbiting CALIPSO ground track and CloudSat satellite and the GOES East Pathfinder Atmospheres Extended (PATMOS-x) geostationary cloud dataset to constrain the processing, transport and redistribution of dust aerosols over the tropical Atlantic Ocean by convection. Cloud top temperature, cloud optical thickness, and cloud top size are used to quantify the sensitivity of wet deposition to the timing and intensity of tropical convection. It is conjecture that when there are more convective clouds present, more dust will be removed from the atmosphere relative to dry deposition alone. Preliminary results provide evidence that convection both reduces downstream dust optical depths and occasionally transports dust to higher altitudes than the main Saharan dust layer. These redistribution and scavenging effects have implications for direct and indirect impacts of dust on radiation balance both locally and downstream of the convection. Further analysis of these complementary datasets may offer new revelations into aerosol-cloud climate interactions.
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