Roles of Mountains in Dust Storms

A study of the dust emission, transport, and deposition is very important for understanding of the various health and social impacts on the local human population, biogeochemical cycle, and the global environmental change. The entry of dust into the atmosphere results from the occurrence of different scales of dust storms resulting from the multi-scale atmospheric processes ranging from the synoptic to near meso-scales of atmospheric motion. In this context, to find the causes of severe dust storms that occurred in the past over north-west Africa, central-north Africa, and Middle east we did a research work. In that study, significant roles of mountains (e.g., Atlas Mountains, Tibesti Mountains, and Sarwat Mountains) were found. For instances, there were a cross mountain flows that produced a leeside inversion layer, which facilitated for the imbalance of the exit region of the jet streak, prior to the large-scale dust storm; generation of terrain (i.e., mountains)-induced downslope winds in response to the transition of the atmospheric flow from a subcritical to supercritical state leading to dust storms; and generation of Kelvin waves supported by the mountains that were responsible for organizing the dust storms and wide distribution and transportation of dust away from the mountains. Regarding this, it is also hypothesized here that similar kinds of roles of mountains are also found in other geographical regions of the world, such as West/North/Northwest China and Mongolia where dust storms occur in the lee of the mountains, (i.e., Tien Shan/ Gobi Altai Mountains/ Khangai Mountains) and involve the long-range transport of atmospheric particulate matter originating from dryland areas. Such events are affecting large numbers of people and their environment especially in spring season because East Asia is the one of the most densely populated areas of the world. In this scenario, these kinds of studies will also be beneficial for analyses of roles of the synoptic features, and identification of their dynamical characteristics are important for evaluating different synoptic dust regimes and their development. So, for the current study, based on the severity of dust storms some cases of dust storms, which occurred in the lee of the respective mountains of China and Mongolia in the past, are considered.

Keywords: Mountains, Dust Storms, Jet streak, Atmosphere