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Free keywords:
CHANDLER-WOBBLE; OCEANIC EXCITATION; ROTATION; REANALYSIS; PERIOD; FIELD; MODEL
Abstract:
The geophysical interpretation of observed time series of Earth rotation parameters (ERP) is commonly based on numerical models that describe and balance variations of angular momentum in various subsystems of the Earth. Naturally, models are dependent on geometrical, rheological and physical parameters. Many of these are weakly determined from other models or observations. In our study we present an adaptive Kalman filter approach for the improvement of parameters of the dynamic Earth system model DyMEG which acts as a simulator of ERP. In particular we focus on the improvement of the pole tide Love number k(2). In the frame of a sensitivity analysis k(2) has been identified as one of the most crucial parameters of DyMEG since it directly influences the modeled Chandler oscillation. At the same time k(2) is one of the most uncertain parameters in the model. Our simulations with DyMEG cover a period of 60 years after which a steady state of k(2) is reached. The estimate for k(2), accounting for the anelastic response of the Earth's mantle and the ocean, is 0.3531 + 0.0030i. We demonstrate that the application of the improved parameter k(2) in DyMEG leads to significantly better results for polar motion than the original value taken from the Conventions of the International Earth Rotation and Reference Systems Service (IERS).
