中国西部土壤冻融起止期和冻结深度及其与气温关系的时空分布特征分析  

The Spatio-temporal Distribution of the Start-end Date and Freezing Depth and their Relationships with Air Temperature over the Western China

作　　者：李悦绮 文军 刘闻慧 陈逸豪 陈亚玲 张强 刘正 LI Yueqi;WEN Jun;LIU Wenhui;CHEN Yihao;CHEN Yaling;ZHANG Qiang;LIU Zhen(Key Laboratory of Plateau Atmosphere and Environment,Sichuan Province,College of Atmospheric Sciences,Chengdu University of Information Technology,Chengdu 610225,Sichuan,China)

机构地区：[1]成都信息工程大学大气科学学院/高原大气与环境四川省重点实验室,四川成都610225

出　　处：《高原气象》2023年第3期657-670,共14页Plateau Meteorology

基　　金：国家自然科学基金项目(41971308);四川省科技计划项目(2021YJ0025);成都信息工程大学科研项目(KYTZ201821)。

摘　　要：冻土变化对寒区基础建设、水文、生态等都有重要影响,在全球变暖背景下,探究土壤冻融过程具有重要现实意义。本文基于中国自然地理特征和冻土特性,划分出中国西部地区(以下简称西部地区)作为研究区域,并利用1981年1月至2020年6月ERA-5地表温度、土壤体积水含量和逐月气温数据,分析了近40年中国西部地区土壤冻融状况、活动层厚度和最大冻结深度空间分布,探讨了冻融状态与气温、海拔的相关性。研究结果表明:西部地区冻融起始时间空间分布具有由高海拔地区至低海拔地区冻结推迟、融化提前的特征。高海拔的藏北高原冻结最早,融化最晚,冻结持续时间最久昆仑山脉上零星区域冻结最长可持续300天以上。海拔低且土壤含水量低的西部西北塔里木盆地,冻结最晚,融化最早,融化持续时间最长,塔克拉玛干沙漠区域融化可维持在280天以上。多年冻土活动层厚度基本都超过2.0 m,只有喀喇昆仑山脉附近的区域才有较大范围活动层厚度低于2 m的区域,青藏高原的季节性冻土冻结深度最大,厚度可以达到2 m以上,塔里木盆地冻结深度最浅,厚度在0.6 m以内。1981-2020年间,西部地区冻结起始日推迟,融化起始日提前,开始冻结和完全冻结起始时间分别以0.089 d·a^(-1)和0.061 d·a^(-1)的速率上升。开始融化与完全融化起始时间分别以0.102 d·a^(-1)和0.156 d·a^(-1)的速率下降。在冻结趋势上升,融化趋势下降的情形下,完全融化持续时间以0.256 d·a^(-1)的速率增加了12天左右,完全冻结持续时间以0.164 d·a^(-1)的速率缩短约11天,研究期间,完全融化起始时间在1996年发生突变,开始冻结起始时间与完全融化持续时间在1997年发生突变。西部地区冻融起始时间整体变化趋势一致,局部地区略有差异,黄土高原开始冻结与完全冻结持续时间分别以0.166 d·a^(-1)和0.405 d·a^(-1)的速率下降最快。�Permafrost have a critical impact on the infrastructure construction,hydrology and ecology in the cold region.Under the background of global warming,it is of great significance to explore soil freeze-thawing cycle over the Western China.Based on the natural geographical and permafrost characteristics,the western region of China is divided into four sub-regions as the study region of this investigation.The ERA-5 surface temperature,soil volumetric water content and monthly air temperature data from January 1981 to June 2020 are to be deployed in analyzing the spatio-temporal distribution of soil freeze-thawing status,the active layer thickness and maximum freezing depth over the western China in the past 40 years.the correlationship between variables of freeze-thawing cycles and air temperature and altitude are discussed.The results show that:the spatio-temporal distribution of the start date of freezing and thawing has the characteristics of delayed freezing and early thawing from high-altitude areas to low-altitude areas over the western region.The high-altitude northern Tibetan plateau freezes the earliest,thaws the last,and freezes the longest.The sporadic areas on the Kunlun Mountains can last for more than 300 days.The Tarim Basin in the west-northwest with low altitude and low soil moisture content freezes the latest,melts the earliest,and lasts the longest.The melting in the Taklimakan Desert can last for more than 280 days.The thickness of the permafrost active layer is basically more than 2.0 m,only the area near the Karakoram Mountains has a large area with a thickness of less than 2 meters.the seasonal frozen soil of the Qinghai-Tibet Plateau has the largest freezing depth,and the thickness can reach more than two meters,and the Tarim Basin shows a shallowest freezing depth,and the thickness is less than 0.6 m.The start date of freezing was delayed over the western region,and the start date of thawing was advanced.The date of start freezing and the date of completely frozen increased at a rate of 0.089

关 键 词：中国西部 土壤冻融 活动层厚度 冻结最大深度 时空分布 

分 类 号：P467[天文地球—大气科学及气象学]