Determination of Statistical Threshold and Synoptic Analysis of Super Cold Temperatures over Maragheh

The present research involves providing a method for determination of threshold rate to recognition Super Cold Temperatures (SCT) over the synoptic station located in Northwest of Iran (Maragheh). In other to determination of SCT the occurrence temperature below the -14.93 C during December to March has been calculated as quantities rate and threshold. Based on this threshold the 10 days was selected as SCT during the above months and the synoptically analysis of cold cloud temperatures has been done over these days. The results of this analyses successfully Identify 3 sea level pressure circulation patterns namely western high pressure pattern with frequency of 5 days, Superimposed high pressure pattern with frequencies of 2 days, Western high pressure pattern with frequency 3 days and Siberian high pressure pattern with frequency of 2 days. Moreover, the classified map of geo-potential height was showed 3 circulation patterns in geo-potential height in a 500 hectopascal level. Calculation and analysis the digital synoptic maps of area was shown that one circulation patterns of 500 hectopascal level dominated over the area alone with weakness of Tropical wind and direction changing of Meridian wind to north have been effected to occurrence a negative temperature advection or transmission of cold air from high altitude area to Maragheh station, which was provided a severe coldness condition and effetely reduces air temperature in area. Furthermore, dominated one of 3 sea level pressure circulation patterns over the area, was increased the effect of cold temperature advection and provide strongly cold condition which is finally call a SCT in area.