Characterization Of Sensible Heat Flux In Minqin Oasis-desert Transition Zone Based On Scintillometer Method

As an important component of the energy balance of the land surface,Sensible Heat Flux(H)is the basis for the analysis of atmospheric dynamics and thermal processes,and it is also the key research object of agriculture,forestry,geography and other related disciplines.This study takes Minqin desert oasis transition zone as the research object,combines the meteorological observatory and vegetation survey data,and uses the large-aperture scintillometer climate footprint model to study and analyze the source area of the subsurface at the point scale of the eddy covariance(EC)system observation and the source area at the kilometer scale of the largeaperture scintillometer observation.A universal function of atmospheric stability suitable for the current subsurface is selected to assess the applicability of the scintillometer under this condition.The following conclusions were obtained.(1)The flux area of the atmosphere at stable conditions is generally larger than the source area of the atmosphere at unstable conditions in both growing and non-growing seasons.Through the analysis of LAS and EC,D＿1993 was determined as the universal function of stability for LAS to calculate sensible heat flux under this subsurface condition.It is proved that the LAS is reliable for H observation under the subsurface of desert oasis.(2)The daily average variation of H at different time scales of the desert oasis subsurface is observed by LAS observation,and it is found that all of them show a single-peaked variation of rising and then falling.The H has obvious seasonal variation and H in spring is larger than it in fall,which is consistent with continental climate characteristics.During the growing season,the heat flux in the subsurface of the desert oasis was greater than that in the non-growing season,with the highest in August and the lowest in October.During the non-growing season,it is highest in March and lowest in December.The heat fluxes in the growing season were generally larger than those in the non-growing season;in the nighttime,the heat fluxes in the growing and nongrowing seasons were both negative,showing that the heat fluxes in the growing season were smaller than those in the non-growing season.(3)In half-hourly scale,H had a highly significant linear relationship with Rn,and other environmental factors had a linear relationship,but lower than Rn;in daily scale,H had a highly significant linear relationship with Rn.In monthly scale,H had highly significant linear correlations with Rn,RH,Ts,Ta and WS.Through multiple linear regressions,it can be concluded that the sensible heat fluxes of desert oasis ecosystems are mainly controlled by Rn and RH.