Comparison of RegCM dust schemes by monitoring an aeolian dust transport episode

Abstract

Dust transport is a cross-boundary phenomenon that affects the environment and impact climate variables. The direct impact of dust transport is the increase in particulate matter concentration alongside its trajectory. The regional climate model, namely RegCM, can be used to predict the dust burden. Either Zakey's or Kok's dust schemes are activated in the chemistry module for the dust transport calculations. In this study, we used each dust scheme to simulate the dust transport event from the Saharan Desert that occurred on February 1, 2015. Our principal aim is to compare transported dust sizes with previously acquired cascade impactor results and evaluate the pros and cons of each scheme. The highest dust concentrations at the sampling location were 332.3 mu g/m(3) and 170.8 mu g/m(3) for Zakey's dust scheme and Kok's dust scheme, respectively. Zakey's dust scheme predicted closer results to the measured value. This was due to the overestimation in the finest size bin, which is between 0.01 and 1.0 mu m. For the remaining sizes, both schemes produced similar results. However, the overestimation in Zakey's scheme deviated the size distribution to finer size, which is not in line with the measured results. The mass median diameter of the transported dust was 1.57 mu m and 0.45 mu m according to Kok's and Zakey's dust schemes, respectively. The measured mass median diameter of dust was 2.6 mu m. Although Kok's scheme predicted the dust size better, both schemes could not simulate coarse size dust transport.