Aircraft Measurements and Modeling of Convectively Generated Dust Storms in Saudi Arabia

Significant uncertainties exist with dust-cloud interactions for which complex microphysical processes link the dust aerosol and cloud properties.  Under almost all environmental conditions, increased aerosol concentrations within polluted air masses will enhance cloud droplet concentration relative to that in unperturbed regions.  The interaction between dust particles and clouds are significant, yet the conditions in which dust particles become cloud condensation nuclei (CCN) are uncertain. In order to quantify this aerosol effect on clouds and precipitation, measurement campaigns were conducted in central Saudi Arabia.

Aircraft measurements of cloud drop size distributions, aerosol size distributions and aerosol mineralogical composition were done in Saudi Arabia in April 2007. During this time a high frequency of severe dust outbreaks due to convectively generated cold pools were observed.

Dust storms and regional background conditions were encountered during the study period. On 9 April 2007 a dust storm (‘haboob’) was sampled with the research aircraft.

The presentation will include a summary of the analysis and results with a focus on the characterization of the dust aerosol and the microphysical properties of convective clouds in central Saudi Arabia as well as new results from WRF-Chem that show dust emissions due to cold pool features in a haboob.