Assimilation of small scale observations with a nested adjoint model

An adjoint limited area numerical weather prediction model with multiple nests has been developed. The adjoint modeling system has the capability to pass gradient information from the finer spaced nest to the coarser spaced domain. Therefore, gradients of scalar functions calculated from small scale features can be computed with respect to the large scale model state. Sensitivity experiments were performed to show that the nested adjoint model produces physically meaningful gradients. Results from data assimilation experiments will be presented at the conference. An ad joint model such as the one presented here, could be in important tool for variational assimilation schemes that intend to make use of high resolution remotely sensed data.