The Effect of Boundary Layer Height Height on Dust Storm in Southwest of Iran (Case Study: February 21-24, 2016)
2019
Ahmadi, Mahmoud | Dadashirodbari, Abbasali | Jafari, Mahnaz
The country is dry and low in the water, the coincidence of this situation and its position in the global rebound belt has brought about very bad conditions. Repeaters in recent years have been affected by the severity and frequency of major events in Iran and, in terms of environmental issues, studying and managing the reduction of its effects is a priority. The purpose of this research is to evaluate the role of the transverse boundary layer in the transition, the conditions creating and exacerbating the disturbance of dust to the southwest of the country. The research methodology first extracted days with dust and a period in which this phenomenon was enormously and intensely studied in the studied area (February 21-24, 2016) for monitoring. The data boundary layer height (BLH) based on the outputs of base ECMWF, Paramtryhay Hvasphr base NCEP / NCAR and Aerosol Optical Depth (AOD) was extracted from MODIS. In addition, in order to evaluate the conditions that create and exacerbate disturbances, the numerical value of Richardson Number was calculated for two radio stations in Ahwaz and Abadan. The results showed that the boundary layer of the atmosphere in creating turbulence and transfer of dust to the country has a significant and non-interlocking role so that in every 4 days the study between the height of the borderline and the optical depth of the particles was greater than 0.70. Unstable airborne conditions such as very deep creeping, strong rotation with a significant positive tau in the axis of the woods, along with negative omega that suggests climb, air instability, and consequently creating uneasy and turbulent conditions in the region, are very favorable and Has strengthened dust removal. The Richardson numerical value in the selected days represents the overrun of the mechanical force of the vortex generator from the thermal deterioration force, which resulted in an uneven and turbulent flow, and the mixing process was performed more easily and quickly.
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