A new algorithm for estimating evapotranspiration based on thermal inertial

Existing methods using remote sensing to evaluate evapotranspiration is based on the land surface balance equation Rn=H+LE+G. First it calculate the surface net radiation flux Rn, soil heat flux G and surface sensible heat flux H, then get evapotranspiration LE using residual method. To calculate sensible heat flux H needs some non-remote sensing parameters, such as air temperature, wind velocity, land surface roughness etc. It also needs interpolation to get regional data and improve the estimation precision. In this paper, downward atmospheric long-wave radiation was retrieved according to thermal inertial, surface radiative temperature and other remote sensing parameters, then used to calculate land surface net radiation flux. Soil heat flux G was parameterized using land surface net radiation flux and apparent heat inertial. For differential thermal inertial can neglect soil texture, it was calculated Bowen ratio. Bowen ratio was used to separate surface net radiation flux and introduced in the land surface balance equation. Surface latent heat flux can be evaluated directly avoiding intermediate link. This new method can evaluate evapotranspiration using complete remote sensing information and avoid the chains of non-remote sensing parameters, such as atmosphere temperature, wind velocity and land surface roughness. So it has more universality, generalization and operability.