Dust storms modeling and their impacts on air quality and radiation budget over Iran using WRF-Chem

The main objective of this research work is to simulate dust storms and evaluate their impacts on air quality and radiation budget over Iran using WRF-Chem coupled model. Two appropriately strong dust storms: May 22–25, 2012 and April 22–25, 2015. According to the results, in the Middle East, countries where sources with highest emission rates are placed include Syria, Iraq, Saudi Arabia, Turkmenistan, and major hot spots inside Iran in the southwestern regions. During both of above storms, very high dust concentrations have been simulated. Domain and simulation period average dust concentration have been estimated to be 402 and 515 μg/m3 over Iran during May-2012 and April-2015 dust storms, respectively. Also, 24 h average dust concentration exceeds 7000 μg/m3 in some regions in the Middle East. Comparison of simulated and observed extinction coefficients and aerosol optical depths (AOD) shows an underestimation for domain averaged AOD. However, spatial and temporal distribution patterns of dust have been well simulated by the developed model. Using two parallel simulations with and without dusts, impacts of dust aerosols on radiation and some meteorological parameters have been evaluated. According to the results, dust aerosols led to negative short-wave (SW) radiative perturbation at the earth’s surface and top of atmosphere (TOA). These radiative perturbations were positive for long-wave (LW) radiation. Stronger negative diurnal perturbations for sensible heat flux, rather than positive nocturnal perturbation which caused 24 h average perturbation to be negative. Nevertheless, the weaker diurnal (negative) rather than nocturnal (positive) surface temperature perturbations made the 24-h average temperature perturbation positive.