An Analysis of the Differences Between Two Seasonal Saudi Arabian Dust Storms Using WRF-Chem
This research focused on understanding the difference atmospheric conditions between two major dust storms in Saudi Arabia. These two types of dust storms occur annually over Saudi Arabia with different seasons, sources, and atmospheric dynamics. We analyzed the Sharav case study in the spring season from 31 March 2015 and the Shamal case study in the early summer season from 09 to 10 June 2015 using the HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory) model to determine the dust source regions and the MERRA (Modern Era-Retrospective Analysis for Research and Applications) data for the large-scale analyses. Dust particles are generated from the Sahara Desert in the Sharav case; however, these particles are generated from the Syrian and Iraqi Deserts in the Shamal case. The large-scale analyses show that the differences in the circulation over much of the troposphere between these two cases cause the different circulations at the surface that impact the evolution of the dust storms differently. The results showed that the Sharav dust event is primarily caused by extratropical dynamics, while the Shamal dust event is forced by more regional dynamics. The WRF-Chem (Weather Research and Forecasting/Chemistry) model was validated against the MERRA data and simulated these cases to estimate the TKE at low-levels for both the Sharav and Shamal case studies which caused high dust concentrations with a maximum magnitude of ≅250 μgm^(-3) and ≅1000 μg m^(-3), respectively. The model calculated the dust emissions within the domain to show the simulated daily rates of dust emissions for both the Sharav and Shamal case studies: a maximum daily average of ≅ 2.5x〖10〗^4 μgm^(-2) s^(-1) and ≅ 9x〖10〗^4 μgm^(-2) s^(-1), respectively.
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