Organization of dust storms and synoptic-scale transport of dust by Kelvin waves

Abstract

Abstract. Based on the large-scale transport of dust driven by the winds parallel to\nthe mountains in the Harmattan, Saudi Arabian, and Bodele Depression\ndust storm cases, a detailed study of the generation of Kelvin waves and\nits possible role in organizing these dust storms and large-scale dust\ntransport was accomplished. For this study, observational and numerical\nmodel analyses were done in an in depth manner. For this, MERRA reanalysis\ndata sets; WRF-simulated high-resolution variables; MODIS Aqua and Terra\nimages; EUMETSAT images; NAAPS aerosol modeling plots; and MERRA-2 dust\nscattering aerosol optical depth (AOD) modeling plots, surface observations, and rawinsonde\nsoundings were analyzed for each of these three case studies. We found that there\nwere meso- β -scale (horizontal length scale of 20–200\u2009km) adjustment\nprocesses resulting in Kelvin waves only in the Harmattan and the\nBodele Depression cases. The Kelvin wave preceded a cold pool\naccompanying the air behind the large-scale cold front instrumental in the\nmajor dust storm. We find that this Kelvin wave organized the major dust\nstorm in a narrow zone parallel to the mountains before it expanded upscale\n(meso- α to synoptic).