1990-2014年西藏季节冻土最大冻结深度的时空变化

最大冻结深度是季节冻土变化的主要指标,也是季节冻土地区工程设计、建设、运营的重要参数。通过斯蒂芬（Stefan）方法计算了1990-2014年西藏地区季节冻土的最大冻结深度,分析了其时空变化特征,结果表明：近25 a西藏地区季节冻土最大冻结深度在空间分布具有垂直分带性、纬度地带性和区域性等规律,基本上呈自西北向东南方向递减的空间分布特征;时间上,在全球气候变暖的背景下,最大冻结深度基本呈逐年减薄的特征。西藏地区季节冻土最大冻结深度与年平均气温和年降水量呈现负相关,随着年平均气温和年降水量的上升,最大冻结深度呈减小的趋势,且最大冻结深度对年平均气温的响应比对年降水量的响应显著。

Temporal and spatial variations of the maximum frozen depth of seasonally frozen soil in Tibet from 1990 to 2014

The maximum frozen depth is the major index of the change in seasonally frozen soil. It is also an important parameter for the engineering design, construction and operation in seasonal frozen soil regions. The maximum frozen depth of seasonal frozen soil in Tibet from 1990 to 2014 were calculated by Stefan's method. The temporal and spatial variations of the maximum frozen depth were analyzed. The results indicated that the spatial distribution of the maximum frozen depth in Tibet had the characteristics of vertical zonality, latitude zonality and regional regularity, which had basically decreased from northwest to southeast from 1990 to 2014. In the context of global warming, the maximum frozen depth had decreased from 1990 to 2014. The maximum frozen depth had a negative correlation with the annual mean temperature and annual precipitation; the maximum frost depth decreased with the increase of annual mean temperature and annual precipitation. Beside, the response of maximum frozen depth to annual mean temperature was more significant than that to annual precipitation.