عنوان مقاله [English]
نویسندگان [English]چکیده [English]
In this paper, for the aim of local climatic change detection, fluctuations of freezing
days in Mashhad during 1951-2000 were studied.
Primary investigations showed that annual mean and absolute temperature have an
increasing trend in the study period. It has a suitable harmony to decreasing trend of
freezing days. So, correlation equation between freezing days and statistical years
calculated by this formula. Y=107.35X-0.53 which it was meaningful and shows –
29.5 days changes in Annual freezing days in mentioned period. Using test of Mann-
Kendal showed two decreasing and decreasing trend, which are significant. We can
observe a falling trend in number of freezing days after 1976.
In next phase, for the purpose of fitting a suitable time series model on the data,
which used in this research, the method of Box-Jenkins was applied. Finally after some
statistical works ARIMA (1,1,0) time series model was selected for the studied data.
The model was able to predict the number of freezing days of Mashhad in the year
2001 with an error about 3.3 percent.