Global warming accelerates the upfreezing of permafrost in arid middle Tianshan Mountains  

作　　者：LI ChuanChuan CHEN YiXin NIE ZhenYu CUI ZhiJiu LIU GengNian 

机构地区：[1]College of Urban and Environmental Sciences, Peking University

出　　处：《Chinese Science Bulletin》2013年第31期3806-3814,共9页

基　　金：supported by the National Natural Science Foundation of China(40971002 and 41101003)

摘　　要：Upfreezing is an important geomorphic process in the periglacial environment.It is a product of cold climate and thus an important part of the cryospheric processes.Based on the long-term positioning observations in the source area of the Urumqi River,this article represents an in-depth discussion of the characteristics of sorted circles and upfreezing mechanisms in the Tianshan Mountains.In the source area of the Urumqi River,the intensity of upfreezing is the highest within the top 25 cm near the surface,while targets with a diameter of 3 cm are least affected by upfreezing.There is no distinct difference between the centre with fine grains and the margin with coarse debris within the same sorted circle in terms of the intensity of upfreezing.The correlation analysis demonstrates that temperature plays an important role in upfreezing and the development of sorted circles.A long-time positioning observation of sorted circles reveals that periglacial landforms are sensitive to regional climate change and respond quickly to the temperature increase of the recent two decades.Enhanced upfreezing was found to be due to increased soil moisture content.Upfreezing is an important geomorphic process in the periglacial environment. It is a product of cold climate and thus an im- portant part of the cryospheric processes. Based on the long-term positioning observations in the source area of the Urumqi River, this article represents an in-depth discussion of the characteristics of sorted circles and upfreezing mechanisms in the Tianshan Mountains. In the source area of the Urumqi River, the intensity of upfreezing is the highest within the top 25 cm near the surface, while targets with a diameter of 3 cm are least affected by upfreezing. There is no distinct difference between the centre with fine grains and the margin with coarse debris within the same sorted circle in terms of the intensity of upfreezing. The correlation analysis demonstrates that temperature plays an important role in upfreezing and the development of sorted circles. A long-time positioning observation of sorted circles reveals that periglacial landforms are sensitive to regional climate change and respond quickly to the temperature increase of the recent two decades. Enhanced upfreezing was found to be due to increased soil moisture content.

关 键 词：全球变暖 天山 区域气候变化 乌鲁木齐河 干旱 冻土 定位观测 温度上升 

分 类 号：P467[天文地球—大气科学及气象学] P313.6