A new method based on remote sensing observations and data assimilation for estimation of evapotranspiration over field crops

Abstract

Much research has focused on the estimation of evapotranspiration (ET) over field crops for agricultural applications such as irrigation scheduling. In this research, a variational data assimilation scheme is developed based on the weak constraint concept. It assimilates surface skin temperature into a simple land surface model for estimation of ET. An automatic differentiation technique is used to derive the adjoint codes to evaluate the gradient of the cost function. After construction of this assimilation system, application case studies are examined to test its performance over field crops. The results show that ET can be retrieved with highly satisfactory accuracy. © 2007 Taylor & Francis Group, LLC.