2009/2010年黄河源区高寒草甸下垫面能量平衡特征分析

The Characteristics of Energy Balance over the Alpine Meadow in the Source Regions of the Yellow River from 2009 to 2010

以青藏高原黄河源玛多为实验区,基于TRM-ZS1气象生态环境监测仪2009年11月1日至2010年10月31日辐射及能量通量观测数据,采用波文比能量平衡法,进行了该区域潜热和感热通量的估算,分析了黄河源区高寒草甸下垫面辐射收支,潜热、感热和土壤热通量在不同季节的分配,对该区域冬季地面加热场强度的变化进行了研究.结果表明:该区域总辐射、净辐射较强,总辐射平均日积分值为18.06MJ·m-2·d-1,净辐射平均日积分值5.95MJ·m-2·d-1,曾观测到高达979.5W.m-2的净辐射通量.全年地表平均反射率为0.30,接近于荒漠和半荒漠下垫面的反射率.植物生长季土壤湿度和冬、春季地面积雪是影响该区域地表反射率的两个最主要因素.该区域感热通量年积分值为742.68MJ·m-2·a-1,潜热通量年积分值为1 388.58MJ·m2·a-1,全年中地表以潜热方式传递热量为主.分季节分析,冬季感热潜热强度相当,春季以感热为主,夏秋季则以潜热为主.土壤热通量年积分值为38.06MJ·m-2·a-1,全年热通量在热量平衡中约占1.8%,但季节分配不平衡,在冬季,有|G|>H+LE,土壤热通量是热平衡最大的分量.该区域地表全年向大气释放热量,地表对大气而言是热源.

Madoi in the source regions of the Yellow River in the Tibetan Plateau was taken as an experimental area.After nearly two years’ observations of radiation and energy flux,radiation budget,energy distribution in different seasons,including latent heat,sensible heat and soil heat flux on alpine meadow underlying surface,the data are analyzed.Also the changes of intensity of surface heating field in winter,and the influence of snow on the surface heating field are analyzed by Bowen ratio energy balance method.It is demonstrated that the total radiation and net radiation are intense.The average daily total radiation is 18.06 MJ·m-2 and the average daily net radiation is 5.95 MJ·m-2,with a maximum of 979.5 W·m-2.The average annual albedo is 0.30,close to that in desert and semi-desert land surface.Soil moisture in the growing season and snow cover period in winter and spring are the two pronounced factors controlling the albedo.Heat budget was negative in these regions in November and December of 2009,indicating the surface absorbing heat from the atmosphere.Sensible heat flux in the region is 742.68 MJ·m-2,and latent heat flux is 1 388.58 MJ·m-2,showing that the main way to transfer heat is latent heat flux all the year round.Seasonally,sensible heat and latent heat are equivalent in winter,sensible heat is principal in spring,and latent heat is principal in summer and autumn.Annual soil heat flux is 38.06 MJ·m-2,accounting for about 1.8% of the total heat balance,showing a seasonal imbalance.In the winter,｜G｜＆gt;H＋LE,which means soil heat flux is the most distinct component in the heat balance.