Hindcasting circulation in the Pacific sector of the Arctic Ocean and the Bering Strait with a nested 4Dvar data assimilation system

Application of the 4D-var data assimilation technique to a system of two one-way nested models is discussed. We consider preliminary results of data assimilation experiments with the nested system involving the Bering Strait high resolution model and a coarser resolution model configured for the Pacific sector of the Arctic Ocean. Oservations obtained both in the Chukchi Sea and the Bering Strait regions are assimilated using the "nested" adjoint models. The nested variational data assimilation scheme allows to obtain a dynamically consistent solution for the both nested models and provides an improved hindcast of the Bering Strait and Arctic Ocean circulations.