Radiative forcing of dust aerosols during a severe dust event in southern Iran

• Published in: Arabian journal of geosciences 2022-03, Vol.15 (5), Article 445
• Main Authors: Rezazadeh, Maryam, Masrour, Parisa Fattahi, RezvaniZadeh, Roya, Jamshidi, Maryam
• Format: Article
• Language: English
• Subjects: Aerosols; Atmosphere; Atmospheric particulates; Configurations; Dust; Dust storms; Earth and Environmental Science; Earth science; Earth Sciences; Environmental health; Heat flux; Heat transfer; Latent heat; Long wave radiation; Net radiation; Optical analysis; Optical properties; Optical thickness; Original Paper; Particulate matter; Pollution; Radiation; Radiation balance; Radiative forcing; Reduction; Short wave radiation; Simulation; Spectroradiometers; Storms; Temporal variations; Visibility; Weather forecasting
• ISSN: 1866-7511; 1866-7538
• DOI: 10.1007/s12517-021-08366-8

Dust storms have adverse socioeconomic impacts on human health and climate. The suspended dust in the atmosphere can also impact the radiation budget. In this study, radiative impacts of a dust storm in southern Iran are investigated during 20–25 November 2016 using the Weather Research and Forecasting model with Chemistry (WRF-Chem), in which the Goddard Chemistry Aerosol Radiation and Transport ( GOCART ) dust scheme is implemented. The WRF-Chem model calculates spatio-temporal variations of atmospheric variables and optical properties of suspended aerosols in the atmosphere. Two simulations have been conducted: a configuration without dust aerosols and a configuration with dust aerosols and their direct radiative forcing. Based on results of the WRF-Chem model, the pollution initiated in southern Iran on 21 November 2016. It is then intensified and transported toward southeast. The center of pollution was in the Persian Gulf and influenced the region until 25 November, with PM10 concentration reaching to more than 10000 μg m −3 . The performance of the WRF-Chem model in terms of simulating the concentration and variation of dust during the event is satisfactory, such that horizontal and vertical distributions of the simulated and the observed dust are quite similar. During the period from 20 to 25 November, the highest reduction of horizontal visibility in southern Iran occurred between morning of 21 and morning of 22 November. Substantial reduction of horizontal visibility also occurred on 23 and 24 November, such that in Hormozgan, Sistan and Baluchestan, and Bushehr provinces, horizontal visibility reached to less than 1000 m during some hours. Maximum aerosol optical depth (AOD) also occurred on 22, 24, and 25 November. The performance of the model in terms of simulating the horizontal extension of the aerosol optical depth is similar to the Moderate Resolution Imaging Spectroradiometer (MODIS) products. Radiative effects of dust aerosols in southern Iran is associated with a reduction in the incoming shortwave and longwave radiation at the surface. The lowest and highest reduction of incoming shortwave radiation occurred in southeastern Iran and Bandar Abbas, respectively. The net radiation (sum of the shortwave and longwave radiation) at the surface is reduced during the dust event, which indicates cooling of the surface by dust aerosols. Results of this study indicates that variation of net radiation at the surface during the pollution period is