A case study for Saharan dust transport over Turkey via RegCM4.1 model

The purpose of this study is to investigate a dust transport episode using atmospheric 3D modeling, satellite data, and in-situ observations. 3D simulations have been used to determine the aerosol optical properties and direct radiative effects of dust particles. In this study, the number of daily exceedances due to dust transport is estimated and, performance of RegCM4.1 model tested quantitatively with the aid of AOD data from AERONET network and PM10 ground measurements. The impact of dust on radiation estimated by the model for the 4-day period. PM10 values for Istanbul for the period between 2004–2010, and Marmara and Aegean Region for March 2008 provided by the Turkish Ministry of Environment were used to select an important episode. Exceedance days were evaluated according to the BSC-DREAM8b model output. We have used the RegCM4.1 model to further investigate the Saharan dust transport in the selected episode 21–24 March 2008. First, observed daily mean PM10 concentrations reach up to 180 μg/m3 in Marmara Region and 160 μg/m3 in Aegean Region, respectively. According to the RegCM4.1 model outputs, station Erdemli presents the highest AOD on 23rd March 2008, around 1.2, which is found to be highest than AERONET observations (AOD of 0.7). In parallel, daily mean AOD in Marmara Region is around 1.0 on the same day. Corresponding simulated column burden is about 1000 mg/m2 in Marmara Region and 750 mg/m2 in Aegean Region, respectively. In terms of radiative effect, daily mean shortwave (all-sky) radiative effect at surface (ToA) is − 62 W/m2 (− 29 W/m2) in Marmara and − 71 W/m2 (− 33 W/m2) in Aegean Region, respectively. In parallel, longwave all-sky direct forcing at surface (ToA) is + 7 W/m2 and (+ 4 W/m2) in Marmara, + 11 W/m2 (+ 4 W/m2) in Aegean Region.