Intercomparison experiment Numerous differences exist between assimilation systems and influence the evaluation of the impact of observations * Observation coverage * Assimilation methodology * Forecast model * Metrics used to compute the forecast sensitivity Possibility to use more appropriate metrics for socio-economic applications * Baseline experiment provided a common context against which three different systems evaluated the impact of observations with the same tool * Differences nevertheless persist in terms of assimilation methodologies and models (e.g., 3D-Var and 4D-Var) * For each system, the total impact of observations evaluated with the LB04 method is consistent with results from OSEs.
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