Impact of Instantaneous Parameter Sensitivity on Ensemble-Based Parameter Estimation: Simulation with an Intermediate Coupled Model

On ensemble-based coupled data assimilation, cross-component parameter estimation, has not been as extensively developed and applied as weakly coupled state and parameter estimation along with cross-component state estimation. This discrepancy is partially attributed to the lack of emphasis on the instantaneous response of coupled model states with respect to parameters across different components. We define so-called response as the instantaneous parameter sensitivity (IPS). Under the framework of sequential assimilation, the prior information heavily relies on the IPS of coupled states with different time scales. Based on the IPS analysis for an intermediate coupled model, a series of twin experiments of state and parameter estimation are conducted.