Studying frost and chilling dates affecting agriculture under climate change (Case study: Mashhad, Tabriz and Qazvin)

Studying the phenomenon of frost and chilling is one of the fundamental researches in the field of Agroclimatelogy and knowing how and when they occur, could be useful significantly in the agricultural sector. Climate change which causes changes in temperature parameters influences the frost. To this end, a research was done so that the beginning of the first frost and chilling in autumn, the last frost and chilling in spring and also period of the frost and freezing at three weather stations in Tabriz, Qazvin and Mashhad would be checked during 1961-2005 as the basis period and during 2005-2050 as the future period. The data of the future period was produced based on output of Hadcm3, under the scenario A1B, using the software of data generator LASR-WG. Then time series of the dates of the first and last frost and chilling in autumn and spring was formed for each year during the periods of the study and the best statistic distribution was fitted for each of them and the possibilities of their happening were calculated. The results showed that at all stations affected by the climate change, the first frost and chilling in autumn will occur earlier and the last frost and chilling in spring will occur earlier and length of frost and chilling period will decrease.