Temporal-spatial Characteristics Analysis of Area-averaged Sensible Heat Fluxes by Large Aperture Scintillometer over Hai River Basin

Abstract

Combined with the measurements of Eddy Covariance(EC) system and Automatic Weather Station(AWS) and after a series steps including data screening,quality assessment,data processing and gap filling,the sensible heat fluxes of Large Aperture Scintillometer(LAS) HLAS and evapotranspiration(ET) were calculated based on the LAS measurements in Miyun,Guantao and Daxing sites over Hai River Basin during 2008-2009.The spatial representation and flux contribution of different land use under unstable conditions were analyzed in January and July over Miyun,Guantao and Daxing sites.Combined with the footprint and the crop phenological phase,the seasonal variation of Hlas over the three sites were compared with Rn in the same period,where Guantao site had the lowest value each month,Hlas in Miyun and Daxing were closed in January and July.Meanwhile,daily Hlas between 9:00 and 15:00 were discussed over the three sites from 2008-2009.Compared to the single peak variation of Miyun site,both Guantao and Daxing sites both had three peak values because of the alternation of crops.Finally,according to the energy closure ratio of EC measurement,the different footprint overlapping ratio between LAS and EC measurements,as well as surface heterogeneity of their non-overlap source area,the difference between Hlas and Hec in Guantao site was discussed.