1980-2017年青海省玉树地区季节冻土变化对气候变暖的响应

The response of seasonally frozen soil depth to climate warming in Yushu Prefecture,Qinghai Province from 1980 to 2017

利用玉树地区5个气象台站1980-2017年逐月温度和最大冻土深度资料,采用线性趋势、相关及主成分分析等统计方法,对玉树地区最大季节冻土深度在气候变暖背景下的变化规律进行了详细探讨,在分析冻土深度与气温及地表温度变化关系的基础上给出最大冻土深度对温度变化的响应模型。结果表明:1980-2017年玉树地区最大冻土深度以10 cm·(10a)^(-1)速率呈显著下降趋势,年代际间变化则表现出"减-增-减-增"波动特征,年内对温度变化的响应在时间上存在一定滞后性;最大冻土深度空间分布呈"西北高、东南低"且具有明显的垂直地带性分布;温度变化对局地季节性冻土的影响有一定差异性,除平均最高地温外其余各温度因子与最大冻土深度变化具有良好的一致性,对冻土影响最大的是平均地温,其次为平均最低气温和平均气温,季节性冻土对气温变暖的响应呈现为退化状态。最大冻土深度变化的温度影响因子主成分回归表明,近年来气温和地温的显著升高是玉树地区冻土退化的最大驱动力,响应模型对估算玉树地区未来最大冻土深度的变化具有较高的可信度。

By using the monthly temperature and maximum frozen soil depth data from five meteorological stations in Yushu Prefecture from 1980 to 2017 and the statistical methods of linear trend,correlation and principal component analysis,the variation of the maximum frozen soil depth in Yushu Prefecture under the background of climate warming was discussed in detail. Based on the analysis of the relationship between the frozen soil depth and surface temperature and temperature change,the response model of maximum frozen soil depth to temperature change was given. The main conclusions are: the maximum frozen soil depth in Yushu Prefecture from 1980 to 2017 had showed a significant decline trend with the rate of 10 cm·( 10 a)-1,and the spatial variation trend had been"high in northwest,low in southeast",and the decadal variation had showed the characteristics of"decrease-increase-decrease-increase". There was a lag in time in response to temperature change. The spatial distribution of the maximum frozen soil depth had been"high in northwest and low in southeast",with an obvious vertical zonality distribution. There was a certain difference in the effect of temperature change on the local seasonally frozen soil. In addition to the average highest surface temperature,the other factors were in good agreement with the variation of maximum frozen soil depth. The most important factor affecting the frozen soil had been average surface temperature,followed by average minimum air temperature and average air temperature,and the response of seasonally frozen soil to temperature warming had been degraded. The principal component regression of the temperature factors affecting the maximum frozen soil depth had indicated that the significant increase in temperature and ground temperature in recent years was one of the largest driving forces on the degradation of frozen soil in Yushu Prefecture,and the response model has a high reliability for estimating the future maximum frozen soil depth in the prefecture.