黑河流域年冻融指数及其时空变化特征分析

Spatial Variability of Freezing-thawing Index over the Heihe River Basin

利用黑河流域气象站点的逐日平均温度数据计算空气及地表冻融指数,并分析其变化趋势以及空间分布。结果表明,黑河流域空气冻结指数、空气融化指数、地表冻结指数和地表融化指数变化范围依次为：673-2135℃·d,1028-4177℃·d,682-1702℃·d,1956-5278℃·d;黑河流域冻结指数出现明显的下降趋势,其中空气冻结指数（1951—2007年）下降速率为56.0℃·d/10a,地表冻结指数（1954—2005年）下降速率为35.4℃·d/10a;融化指数表现为上升,其中空气融化指数（1951—2008年）整体以每年47.8℃·d/10a的速率上升,地表融化指数在1954—1975年以135.9℃·d/10a的速率下降,在1976—2006年以185.3℃·d/10a的速率上升;黑河流域各站点冻结指数受海拔及纬度双重影响,而融化指数则主要受海拔影响;年平均气温与冻融指数有非常强的线性关系。

Air and ground freezing-thawing index for stations in the Heihe River Basin were calculated based on daily mean temperature,and its variation characteristics and time series were analyzed. The results showed that,the freeing index over the Heihe River Basin were influenced by elevation and latitude while the thawing index mainly influenced by elevation; air freezing-thawing index and surface freezing-thawing index ranges were 673 -2 135 ℃ ·d,1 028 - 4 177 ℃ ·d,682 - 1 702 ℃ ·d,1 956 - 5 278 ℃ ·d,respectively; freezing index exhibited decreasing trend and the slopes of air freezing index（ 1951-2007） and surface freezing index（ 1954-2005）were- 56. 0 ℃ ·d /10 a and- 35. 4 ℃ ·d /10a; thawing index increased and the liner tendency of air thawing index was 47. 8 ℃ ·d /10 a during 1951-2008; surface thawing index decreased during 1954-1975 with a rate of- 135. 9 ℃ ·d /10 a and increased during 1976-2006 with a rate of 185. 3 ℃ ·d /10 a. Freezing index was influenced by both elevation and latitude while thawing index was mainly controlled by elevation in the Heihe River Basin. We also found that there was a strong liner relationship between mean annual air temperature and freezing-thawing index.