عنوان مقاله [English]
Climate change has serious consequences on the environment by changing climatic patterns and disrupting the order of ecosystems. Changes in these patterns can lead to global warming and the consequences of floods, extreme heat and cold, more frequent droughts, etc. This is due to the great size and special natural features of Khorasan and factors such as the presence of high mountain ranges and desert areas, distance from water bodies, and different winds, which have caused a variety of climates in each of its regions. The purpose of this research is to investigate 16 temperature limit indicators in Greater Khorasan region in order to reveal climate changes. Methodology: 25 years of daily temperature statistics of synoptic stations (14 stations) during 1987-2011 were used based on statistical analysis. The results showed that limited stations such as Qochan and Sabzevar show a decreasing trend in a number of temperature limit profiles (CSDI, TR20, TNX, FD, TN10P), in other stations more than 90% are experiencing temperature changes from They are heating type. Among the indices, in the first order, the indices of summer days, hot days, maximum maximum temperature, hot nights, length of hot period, 100% increase trend and cold days index 100% show a decrease trend. Also, the indicators of hot nights and maximum minimum temperature, minimum temperature with more than 85% increasing trend and cold nights index with 85% decreasing trend are in the second place. In the third place, the indicators of the minimum and maximum temperature, the length of the growing season are increasing with 71 and 69%, respectively, and the index of freezing days with 71% of the decreasing trend. Therefore, it can be concluded that Greater Khorasan has experienced severe temperature changes, such as heating, during the last 25 years, and according to the behavior of the indicators, the intensity of these changes has increased in the coming decades.