Shu-Hua Chen (University of California Davis)
"Response of a MCS and its cold pool formation to dust-radiative forcing over Sahara Desert
This study examines the role of dust in the development of a mesoscale convective system (MCS) over the central-west Sahara, and how a cold pool from the MCS affected wind-blown dust emissions. Moderate Resolution Imaging Spectrometer (MODIS) and Multi-angle Imaging SpectroRadiometer (MISR) retrieved aerosol optical depth (AOD) and Meteosat Second Generation dust-enhancement product were used to examine a dust outbreak that occurred between 13 and 15 August 2005. Satellite retrieval data also revealed that a moist tongue intruded into the Sahara and caused a MCS to develop near the edge of a strong moisture gradient. Using reanalysis we found that an African easterly wave merged with the Saharan heat low to form an intense surface low-pressure system. High wind speeds associated with the low-pressure system emitted a significant amount of dust, which potentially impacted the development of the MCS over desert. Cold pool outflow from the MCS then resulted in additional dust emission, with implications for long range transport. The Weather Research and Forecasting dust model was modified and used to numerically study the MCS case. The model reasonably reproduced the northward intrusion of the moisture tongue, the AOD, and the formation of MCS. Numerical experiments with (ON) and without (OFF) dust-radiation interactions were conducted to investigate the influence of dust-radiative forcing on the MCS and cold pool development. Mechanisms of the MCS development over desert, influences of dust-radiative forcing on the MCS’ environment, and subsequent impacts of dust on the MCS development and cold pool intensity were investigated and will be presented."