Abstract:
The purpose of this study is to study the probable deviation of temperature and precipitation elements in the northwest of the country from normal. For this purpose, at first, the time series of the minimum temperature and the monthly precipitation of the selected synoptic meteorological stations of the region for the past half century (1956- 2005) were collected and adjusted. The statistical deficiencies of some series were corrected by the double mass method, in order to investigate and recognize the changes of the time series The Kendall test and the Mann-Kendall statistical-graphic statistical test were used and the type and time of the change of data were determined. The results of the research show that assuming randomness of the data It is strongly rejected and the trend situation is dominant on the data. Based on the graphic diagrams, changes in the parameters u and u mean minimum temperature and rainfall in the region over the past half century have been changed. These changes are short-term fluctuations and trend. This is most evident in most time series since the 1990s. In terms of the distribution of time and location of major precipitation in the region, especially in the east and west of Lake Urmia, sudden changes and significant mutation And during the 1990s and 2000s, the steep slope was on the downside of the medium-temperature minimum and precipitate series. In terms of the average temperature, there is a minimal contrast between the west and east of the region. Thus, in the west of Lake Urmia mutations and sudden changes are significant in the negative direction. But in the eastern lake (Tabriz), a significant temperature mutation in most of the months of the year is a positive one, which is likely to be a recent phenomenon of recent urbanization in this regional contradiction. In northern and southern parts of the region, no significant changes were observed in terms of temperature and the normal state was observed.
