On the opposing roles of air temperature and wind speed variability in flux estimation from remotely sensed land surface states

摘要: [1] In semi-arid regions the evapotranspiration rates depend on both spatial distribution of vegetation and soil moisture, for a given radiation regime. Remote sensing can provide high resolution spatially distributed estimation (o ∼ 10–100 m) land surface states. However, data near air properties are not readily available at same often taken as uniform over greater region. Concern how this scale mismatch might lead to erroneous flux estimations motivates effort. This paper examines relative roles variability in two dominant atmospheric states, wind speed temperature, fluxes. The study is conducted with Large Eddy Simulation (LES) model Atmospheric Boundary Layer (ABL), where boundary conditions by energy balance based remotely sensed data. Simulations have been performed late morning hours clear-sky summer days during SGP97 experiment different wetness an area characterized contrast canopy cover, roughness between vegetated dry bare areas. Spatial density effects temperature Ta, through partitioning, U, via roughness, leading local variations 5 m above ground order 1 K m/s, respectively. show that Ta tends decrease sensible heat H (− 30 W/m2) areas increase it (+30 dense vegetation, thus reducing total fluxes those would be estimated constant observed previous studies. U (+50 W/m2), while having negligible increasing variance when considered together, combined effect limited ( 50%) evaporative fraction EF.