Observed permafrost thawing and disappearance near the altitudinal limit of permafrost in the Qilian Mountains  

作　　者：Wen SUN Tingjun ZHANG Gary D.CLOW Yan-Hua SUN Wen-Yu ZHAO Ben-Ben LIANG Cheng-Yan FAN Xiao-Qing PENG Bin CAO 

机构地区：[1]Key Laboratory of Western China's Environmental Systems(Ministry of Education),College of Earth and Environmental Sciences,Lanzhou University,Lanzhou 730000,China [2]Institute of Arctic and Alpine Research,University of Colorado Boulder,Boulder 80303,USA [3]National Tibetan Plateau Data Center,Key Laboratory of Tibetan Environmental Changes and Land Surface Processes,Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100101,China

出　　处：《Advances in Climate Change Research》2022年第5期642-650,共9页气候变化研究进展（英文版）

基　　金：supported by the Strategic Priority Research Program of Chinese Academy of Sciences(XDA20100103);by the National Natural Science Foundation of China(41801028,42171120)。

摘　　要：Permafrost degradation has been widely reported on the Tibetan Plateau(TP).However,directly observed evidence of permafrost thawing processes and degradation rates are very limited,although it is expected to be prevalent near the periphery of a permafrost area.Here,we report permafrost changes and disappearance in the Qilian Mountains(northeastern TP)based on three boreholes instrumented along a 100 m transect during 2014–2021.Our results show that permafrost has significantly degraded in the study area:the mean downward thawing rate from the permafrost table was about 0.16 m per year while the mean upward thawing rate from the permafrost base was about 0.23 m per year.We estimate the mean lateral degradation rate of permafrost in this area was∼4.14 m per year.More dramatically,the 1.5 m thick permafrost layer at one of the boreholes thawed completely between April of 2018 and December of 2019.Our results indicate that changes in climatic condition may have played only a limited role in controlling the active layer thickness in the vicinity of the altitudinal limit of permafrost;moisture content and soil conditions play key roles in site-specific permafrost thawing.This study provides new quantitative insights for understanding changes near the altitudinal limit of permafrost,and we suggest that land surface models or Earth system model studies of the lateral heat exchanges should be implemented in order to better represent permafrost thawing processes.

关 键 词：PERMAFROST Permafrost degradation Permafrost lateral thawing Qilian Mountains 

分 类 号：P642.14[天文地球—工程地质学]