Estimation of evapotranspiration over heterogeneous surface based on HJ-1B satellite

Evapotranspiration plays an important role in the surface-atmosphere interaction. Remote sensing has long been identified as a technology capable of monitoring ET. But spatial scale problem has a great effect on the accuracy of the ET retrieval by satellite. The objective of this paper is to reduce the uncertainty produced by spatial scale problem based on the spatial characteristic of HJ-1B data. Firstly, the temperature is sharpened to 30m spatial resolutions associated with visible-near-infrared bands. Then net radiation, soil heat flux and sensible heat flux of sub pixel are calculated at 30m resolution using one-source energy balance model. Finally, the fluxes are averaged to 300m resolution and latent heat flux is computed as residual of surface energy balance. The result shows that Temperature sharpening and flux aggregation (TSFA) method reduces the uncertainty produced by spatial scale problem, and it can capture the land surface heterogeneities and associated uncertainties in a way.