黄河源区玛曲土壤冻融过程中地表水热交换特征分析  

Characteristics of Surface Water and Heat Exchange during Soil Freezing And Thawing of Maqu Station in the Source Area of the Yellow River

作　　者：张戈 赖欣 刘康 ZHANG Ge;LAI Xin;LIU Kang(College of Atmospheric Science,Plateau Atmosphere and Environment Key Laboratory of Sichuan Province,Joint Laboratory on Climate and Environment Change,Chengdu University of Information Technology,Chengdu Plain Urban Meteorology and Environment Observation and Research Station of Sichuan Province,Chengdu 610225,Sichuan,China;Civil Aviation Flight University of China branch in Suining,Suining 629000,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/气候与环境变化联合实验室/成都平原城市气象与环境四川省野外科学观测研究站,四川成都610225 [2]中国民用航空飞行学院遂宁分院,四川遂宁629000

出　　处：《高原气象》2023年第3期575-589,共15页Plateau Meteorology

基　　金：第二次青藏高原综合科学考察研究项目(2019QZKK0105);国家自然科学基金项目(42075081,41971308,42075019,41905008)。

摘　　要：土壤冻融过程显著影响地表含水量和能量收支变化。利用玛曲2017年8月至2018年7月的土壤温度/湿度、涡动观测资料以及公用陆面模式(Community Land Model,CLM)最新版本CLM5.0的模拟资料,其中冻结过程阶段的辐射和能量通量使用模式模拟的数据,通过分析土壤冻融过程中土壤温湿度、地表能量平衡各分量的时间演变特征,探讨冻融过程中地表水热交换的特征。数据分析表明:(1)土壤冻融过程包括冻结过程、完全冻结、消融过程及完全消融四个阶段,各阶段中的土壤温度/湿度、辐射和能量通量存在明显的日变化,在冻结过程和消融过程阶段,土壤湿度随土壤温度变化显示出明显的日冻融循环。(2)冻融过程通过影响表层土壤水分影响地表辐射收支和能量分配。冻融过程中土壤中的水相变为冰,改变下垫面性质影响地表辐射收支。土壤中的液态水通过相变影响地表潜热通量,完全消融(冻结)阶段,地气之间能量交换以潜热(感热)通量为主。相比于以潜热通量为主的冻结过程阶段,消融过程阶段净辐射通量逐渐增大,地气之间能量交换主要受感热通量影响。土壤中水分的昼融夜冻导致频繁的潜热通量释放影响地表热通量。土壤热通量在冻结过程(G_(0)=-9.1 W·m^(-2))和消融过程阶段(G_(0)=3.4 W·m^(-2))绝对值大于完全消融阶段(G_(0)=1.2 W·m^(-2)),土壤日冻融循环加强地表热通量交换。(3)能量闭合率为感热、潜热通量之和与净辐射通量、土壤热通量之差的比值。冻结过程、完全冻结、消融过程和完全消融阶段平均能量闭合率为1.44、1.56、0.99和0.81,消融过程和完全消融过程能量闭合率更趋近于1。土壤中存在日冻融循环时,冻结过程阶段土壤中的水冻结释放热量,高估土壤热通量从而高估能量闭合率,消融过程阶段土壤中的冰融化吸收热量,低估土壤热通量从而低估能量闭合率,影响地�Land surface moisture content and energy budget are significantly affected by the soil freeze-thaw process.From August 2017 to July 2018,soil temperature,soil moisture,eddy data from observation and the simulation data of Community Land Model 5.0(CLM5.0)of Maqu were used to analyze the time evolution characteristics of soil temperature and moisture,radiation and energy flux in soil freeze-thaw process,and to explore the characteristics of surface water and heat exchange during freezing and thawing.The observed data of radiation and energy flux are replaced by simulated data during the freezing process.The results show that:(1)Soil freeze-thaw process includes four stages:the freezing,completely frozen,thawing,and completely thawed stages.Soil temperature,soil moisture,radiation and energy flux have obvious diurnal changes at each stages.In the freezing and thawing stages,the soil moisture change with soil temperature shows an clear diurnal freeze-thaw cycles.(2)The water phase change in the soil during freezing and thawing changes the nature of the underlying surface,and affects the surface radiation budget.The phase transition of water affects the surface latent heat flux,in the completely thawed stage,the surface energy exchange is dominated by latent heat flux.The surface energy exchange is dominated by sensible heat flux in the completely freezed stage.Compared to freezing stages,which surface energy exchange is dominated by latent heat flux,the net radiation gradually increase in thawing stage,leading to sensible heat flux increase.The soil water melts during the day and freezes at night,resulting in frequent release of latent heat flux,affecting the surface energy exchange.The absolute value of soil heat flux in freezing(G_(0)=-9.1 W·m^(-2))and thawing stage(G_(0)=3.4 W·m^(-2))is greater than that in completely thawed stage(G_(0)=1.2 W·m^(-2)).Daily freeze-thaw cycle strengthens surface heat flux.(3)The energy closure rate is the ratio of the sum of sensible heat and latent heat flux to the difference be

关 键 词：土壤冻融 能量通量 水热交换 数值模拟 

分 类 号：P422.4[天文地球—大气科学及气象学]