عنوان مقاله [English]
نویسندگان [English]چکیده [English]
In this study, spatial and temporal characteristics of convective systems in southwest of Iran has assessed with Global merged IR brightness temperature data (acquired from Meteosat, GOES and GMS). Convective systems detected and traced on the basis of 228 K and 1000 Km2 temperature and area thresholds, respectively. In total , 268 convective systems identified at heavy precipitation times (based on WMO with precipitation of more than 10mm during 6 hours and also shower phenomena recorded at least in three stations). Results show that December and April with 69 and 67 cases respectively has the most occurrence and February with 5 cases has minimum occurrence. The results Such as a fairly great number of large and long lived systems shows the importance of dynamic factors in formation of MCSs in this region. The most frequency of movement direction was southwest-northeast (53%) and west- east (38%), thus movement direction of this system conform with middle level flow and controlled by it. The analysis revealed that convective systems initiation and termination location was influenced by topography. In general, they were most predominant across northeast of study area with a decreasing southwest ward gradient, that follows topography, but this pattern was different in cold and warm months, so that we have observed the most conformity in warm months and the least conformity in cold months.