Knut A. Liseter and Laurent Bertino, Nansen Environmental Center
A coupled sea-ice model is used to perform several assimilation experiments using sea ice concentration derived from passive microwave sensors (SSM/I) and synthetic ice thickness estimates designed to simulate CryoSat ice thickness measurements. The ocean model used in the experiments is HYCOM, whereas the ice model is a one-category dynamic-thermodynamic sea-ice model. The assimilation method used in the experiments is the Ensemble Kalman Filter (EnKF).
The assimilation of sea-ice variables illustrate the importance of updating both the state of the ocean and the state of the ice cover in the assimilation. It is also demonstrated that dynamical error evolution, as provided by the EnKF method, is important to properly characterize the error statistics which change depending on season and the location of the ice edge. The method is applied real-time in the TOPAZ system for assimilating ice-concentration.