我国北疆地区1961—2017年冻融指数的变化趋势

利用我国北疆地区49个主要气象站1961-2017年的逐日平均气温观测值计算了年冻融指数，并分析其变化趋势及分布特征。结果表明：北疆地区冻结指数出现明显的下降趋势，下降速率为51.6℃·d·（10a）^-1。冻结指数的范围在509~2 304.9℃·d之间，平均值为1 240℃·d。北疆地区融化指数出现明显上升趋势，上升速率为73.9℃·d·（10a）^-1。融化指数的范围在526.4~4 531.1℃·d之间，平均值为3 516℃·d。冻结指数表现出在经纬度和海拔较低的准噶尔盆地和伊宁地区较小，在海拔高的高山地区如阿尔泰山和天山山脉较大；融化指数与之相反。北疆地区冻结指数受经纬度及海拔的综合影响，融化指数则主要受海拔影响；年平均气温和冻融指数有非常强的线性关系。

Variation trends of freezing and thawing index in North Xinjiang from 1961 to 2017

Annual mean freezing index and thawing index for 49 stations in north Xinjiang were calculated based on daily mean temperature from 1961 to 2017, and their variation trends and distribution characteristics were analyzed. The results showed that freezing index in North Xinjiang showed an obvious decreasing trend at a rate of 51.6℃·d·(10a)^-1, ranging from 509 to 2 304.9℃·d, with an average value of 1 240℃·d. Thawing index showed an increasing trend with a rate of 73.9℃·d·(10a)^-1, ranging from 526.4 to 4 531.1℃·d, with an average of 3 516℃·d. Freezing index was smaller in Junggar Basin and Yining Prefecture characterized by lower latitude and elevation, and larger in high elevation areas, such as Altai and Tianshan Mountains, while thawing index was opposite. Freezing index was dependent on longitude, latitude and elevation, while thawing index was mainly controlled by elevation in north Xinjiang. It was also found that there was a distinct linear relationship between annual mean temperature and freezing and thawing index.