Validation of Satellite-Derived Sensible Heat Flux for TERRA/MODIS Images over Three Different Landscapes Using Large Aperture Scintillometer and Eddy Covariance Measurements

Sensible heat flux (H) is the key component of the earth surface energy balance, which plays a vital role in the evolution of regional climate. The regional and global scale estimation of H is critical and challenging due to the validation of satellite-based estimation of surface energy balance components. This paper focused on the validation and performance evaluation of the satellite-derived H based on a single source remote sensing model in regional scale over three distinct landscapes in northwest China during May to September 2015 using data from TERRA-MODIS and meteorological observations. The results indicated that the remote sensing model with MODIS scenes performed well for the purpose of H estimation, but the influence of different landscapes was noticeable. The satellite-derived H (MODIS-H) was compared with the large aperture scintillometer (LAS)-measured H (LAS-H) and eddy covariance (EC)-measured H (EC-H) over the three different land surfaces. The root-mean-square errors (RMSE) of MODIS-H with respect to LAS-H were 31.63 W/m² over alpine grassland, 44.07 W/m² over croplands, and 112.98 W/m² over mixed forests. The aggregated values (from May to September) of mean and standard deviation showed that the MODIS-H was moderately overestimated with fewer fluctuation over alpine grasslands, slightly overestimated with moderate fluctuation over croplands, and highly overestimated with higher fluctuation over mixed forests. The larger RMSE and over estimations could be explained by the vegetation heterogeneity, the wind speed profiles, and the complicated thermodynamic states.