تعیین دمای ریزش برف و ضریب برف‌ در استان‌های برف‌خیز ایران

Most of the precipitation in the mountainous basins is as snow which has an important role in generation of the runoff in the spring and summer. So determining the temperature of snow and snowy coefficient is important to proper management of water resources. In this research, amounts of temperature, dew point depression, and saturated vapor pressure were extracted from 30 Synoptic stations in snow-rich provinces and the frequency, relative frequency and cumulative frequency of snowfall in different temperature ranges were determined for each station. To analyze the snowfall occurrence frequency, the appropriate distribution function was fitted on the temperature data and the possibility of snowfall in a giventemperature and less than it was calculated. Also, to  predict the type of precipitation (rainfall or snowfall) the correlation between the dew point temperature and saturation deficit in the snowfall occurrence was determined and snow coefficient was calculated using the relationship Chandra coefficient. Our results indicated that  the snowfall temperature mainly has the best fit with Gamble and Normal distributions.  Also, the temperature of snow fall in the snow-rich provinces of the country changes from 1.77 to -2.54°c . Results of occurrence frequency analysis with probability distribution functions revealed that the snowfall temperature decreased and snow coefficient increased with increasing the return period. The highest snowy coefficient with an amount of  72.96 in return period of 200 years is related to Maraghe.