We assumed that the complete set of observations can be split in observation subsets with independent errors (R is block-diagonal); Regions : HN, HS, TROPICS; Obs_types : AI, GO, PR, SF, SW, AMSU-A, AMSU-B, RAOB; Computation of DFS in MSCs 3D-Var and 4D-Var systems (Lupu, 2009) DFS for each type of observations
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