The zoning of spatial and temporal distribution of the beginning, the end, and the frequency of freezing in Khorasan Razavi province

One of the forms of temperature variations is the sudden fluctuations of temperature, in particular the drop to the freezing point. The freezing is referred to as a condition in which the temperature of the earth's surface and the objects in contact with it is reduced to zero or less than zero degrees Celsius. This study has been done to investigate the temporal and spatial distribution of start and end frost during 1989-2011 in Khorasan Razavi province. Thus, the long-term daily minimum temperature data from 10 synoptic and evaporation stations including Mashhad, Golmakan, Kashmar, Neishaboor, Sarakhs, Gonabad, Sabzevar, Torbatjam-e-Jam, Torbat-e Heidarieh and Quchan have been used. To determine the beginning and end of frost days, the days converted into Julian day and then Minitab and ArcGIS software were used for charting and mapping the spatial and temporal distribution of frost. The result showed that in the northern regions compared with western and southern regions, the frost began earlier and ends later. Frost period in the province increased from south to north, and it would limit the growth period in these areas. Frequency of freezing in the northern areas is more than southern and western parts.