摘要
根据鄂陵湖畔高寒草地站点2011-2013年的观测数据,分析了冻结期高寒草甸地表能量通量平衡特征,在假定冻结期土层中各相态水的质量近似稳定的基础上,对热储项进行了定量分析。由于缺少对积雪深度的直接观测,根据地表反照率定义了积雪期。首先对冻结期地表能量特征进行了比较,发现无积雪时地表波文比多数时候大于3,而在积雪期,波文比大多时候小于0.5。有积雪时土壤各层温度平均日较差都显著地减小,其中0.05 m处土壤温度日较差相较于无积雪时减少4℃。伴随温度日较差减小,积雪期土壤内相变过程也会减弱,引起土壤湿度变化幅度的减少。积雪层可以吸收短波辐射,因此有积雪存在时,地表能通量传输过程需重新考虑。计算热储后发现,非积雪期土壤温度变化和相变过程贡献的热储项分别占不闭合能量(简称占比)的69%和12%,这个比例在阴天和晴天也会存在不同。在积雪期,积雪热储项占比为88%,而土壤热储占比仅为10%左右。与晴天相比,阴天积雪热储占比下降,土壤热储占比上升。这说明短波辐射增强会迅速增加积雪吸收的热量,但对积雪下冻土的影响却很小。对于冻结期中非积雪期闭合度的分析,同时考虑土壤温度和相变热储时闭合度会增加0.01~0.02,且阴天闭合度整体大于晴天。
Based on the observation from a flux site over alpine meadow near Ngoring Lake,the surface energy flux balance status was studied in frozen periods from 2011 to 2013.The snow-covered period is defined as the observed surface albedo greater than 0.4.The Bowen-ratio in no-snow period was usually more than 3,while in the snow-covered periods less than 0.5.The soil heat storage was mainly focused in this study.The total mass of water in soil(liquid and solid form)was assumed to be changed little during the frozen period based on observation fact.The soil heat storage was contributed by two kinds of process.The first is due to the change in soil temperature,and the second is due to free-thaw cycle within soil.In no-snow period,the soil heat storage rates due to temperature change and freeze-thaw cycle have contributed 69%and 12%of the unbalanced surface energy fluxes,respectively.The ratio between these two kinds of heat storage depend on the cloudiness.The free-thaw cycle was more significant in a clear day than in a cloudy day.The closure ratio will increase a little when take both two kinds of process into consideration.While during the snow-covered periods,the heat storage in snow layer accounted for 88%,while the soil heat storage only accounted for nearly 10%of the unclosed energy fluxes.The ratio of heat storage between in soil and snow also changed with cloudiness.The heat storage in snow was more dominant in a clear day than in a cloudy day.
作者
齐木荣
马千惠
杨清华
吴仁豪
吕世华
孟宪红
李照国
奥银焕
韩博
QI Murong;MA Qianhui;YANG Qinghua;WU Renhao;LÜShihua;MENG Xianhong;LI Zhaoguo;AO Yinhuan;HAN Bo(Guangdong Province Key Laboratory for Climate Change and Nature Disaster Studies,School of Atmospheric Sciences,Zhongshan University,Zhuhai 519082,Guangdong,China;Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai 519082,Guangdong,China;Key Laboratory of Land Surface Process and Climate in Cold and Arid Region,Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,Gansu,China;College of Atmospheric Sciences,Chengdu University of Information Technology Plateau Atmosphere and Environment Key Laboratory of Sichuan Province,Chengdu 610225,Sichuan,China)
出处
《高原气象》
CSCD
北大核心
2020年第6期1270-1281,共12页
Plateau Meteorology
基金
国家重点研发计划项目(2019YFA0607004)
粤港澳大湾区典型物质源汇过程及其生态效应联合基金项目(U1901209)
国家自然科学基金项目(41675015)。
关键词
青藏高原
鄂陵湖
热储
积雪
Qinghai-Xizang Plateau
Ngoring Lake
heat storage
snow
