Formation and Evolution of a heavy dust storm over Middle East: A Numerical Case Study

Atmospheric processes and their interactions with ground surface responsible for formation and evolution of a heavy dust storm are important for identifying dust transport pathways. Spatial and temporal distribution of Middle Eastern dust for a severe dust event during 4-8 July 2009 was analyzed by Weather Research and Forecasting with Chemistry (WRF/Chem) model simulations, in-situ and remote sensing observations. Analyses of simulated Weather conditions, during maximum dust concentrations in low level, were occurred with high pressure gradient and high advection in present of cyclonic system. This condition was caused strong surface wind shear over known dust emission sources over Iraq. This frontal cyclone was forced soil to eroded and dust to dispersed and transported for a significant long distance. The fine dust particles (< 1μm) with significant concentration were crossed Zagros mountain range and affected Tehran mega-city on 6 July 2009 and after two days left Iran from North East. The simulation results were found to well reproduce spatial and temporal distribution of mineral dust concentrations according to visible images based on the high-spatial resolution NASA MODIS, in-situ measurements of PM10 in Tehran air quality monitoring network and reported hourly visibility in synoptical stations network. The performance of WRF/Chem was acceptable for simulation of spatial and temporal distributions of dust storm along affected area during simulated period.

کلیدواژه ها:

AOT ، Dust storm ، MODIS ، Tehran ، WRF/Chem