The Analysis of the relationship between Atmosphere circulating patterns and winter low extreme temperature in Ardabil province in 1380th decade

In this study, in order to analysis of the relationship between atmospheric circulation patterns with the occurrence of extreme low temperatures in the winter of Ardebil province in 1380 decade And specify the process of this temperatures with mean daily, monthly and yearly temperatures of four synoptic stations in the region in Excel software, sixth-order linear and polynomial trend drawn, And the percentage of temperature changes in each three cold month of the season with time, (y) predictive equation and process line was evaluated. Also using spss software correlation between minimum temperatures, altitude and latitude of eleven stations of Ardebil province were analyzed. At the final step, among of the daily minimum temperature, 15 days that had lower extreme temperatures were elected, also in order to depicting weather maps in Grads software necessary data from (NOAA) website were obtained and (slp) and (HGT) maps, Thermal wind (stream of temperature) of 500 HP and temperature profile of representative day And one day before and one day after the event depicted in the named software and from analyzing low-pressure and high-pressure systems positions, replacement of pressure centers and its tabs at ground level, The establishment and move of low level troughs at the level of 500 HP atmosphere and their performance in cold landslides generating extreme low temperatures were analyzed. The results are presented as below. A. There is a very strong relationship between the minimum annual temperature and altitude in Ardabil province. Or in other words the role of height in the region minimum temperatures excels latitude. B. In general, the trend shows decline in winter extreme temperatures of Ardebil province in recent decades. C. On all days of the study, the cause of the occurrence of winter extreme temperatures in the ground level is due to area location under the exposure of high pressure tongues or its center at the 500 HP atmospheres, locating the area in front of the stack (behind the trough), landing area or proximity with landing base causes cold air higher latitudes and cause of low extreme temperatures in this province (Advection frost). D: also in some cases, the proximity of some of the studied stations in the region with high altitudes or station itself high altitude and long wave radiation (the albedo of the Earth) intense cold and temperature drop.