Development of NAVDAS-AR: non-linear formulation and outer loop tests

摘要: NAVDAS-AR is the 4DVAR extension of United States Navy’s operational 3DVAR data assimilation system, NAVDAS (Naval Research Laboratory Atmospheric Variational Data Assimilation System), where AR stands for accelerated representer. Like NAVDAS, cast in observation space, and an space formulation algorithm, contrast to European Centre Medium-Range Weather Forecasts which analysis algorithm. In this paper we show how inner loop linear solution can be augmented by outer iteration procedure that introduces non-linear effects form a first-order Taylor series expansion. The problem then solved iteratively as sequence problems. We results strategy, first loop, ‘linear’ solution, modified second both term calculation innovations, linearized background model about ‘trajectory’ from loop. also strategy allows better observations surface wind speed precipitable water, compared NAVDAS.