The influence of the polar front jet stream on the formation of dust events in the southwest of Iran

Dust events are among the climatic hazards which may occur the year over in the southwest of Iran. The goal of this research was to investigate the role of the Polar Front Jet Stream (PFJ) as one of the most important synoptic patterns affecting the formation of dust events in the southwest of Iran during statistical period (1998-2012). The research method was a combination of statistical-synoptic and remote sensing analyses. The frequency of occurrence, duration and intensity of dust events were studied by using hourly data of 5 synoptic weather stations. Also, climatic stability condition considering climatic conditions of ground level and 500 hpa level was investigated by using networked data obtained from the NCEP. Dust detection was done by using the data of Meteosat 7 satellite and MODIS sensor of Aqua satellite. In addition, weather conditions were analyzed simultaneously with dust events using dust measurement indices such as Aerosol Absorption Index (AAI) of TOMS sensor and Aerosol Optical Depth (AOD), and concentration rate of dust and visibility extracted from the output data of the numerical simulation model (COAMPS). Statistical results showed that the main factor of more than 20 % of total dust events in the southwest of Iran was the synoptic pattern of the PFJ, leading to the formation of dust events in the cold period of the year. Finally, synoptic analysis of weather maps and satellite images clearly indicated the effective role of PFJ in the formation of dust events of cold periods in the southwest of Iran.