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Abstract:
The modeled geophysical angular momentum excitation functions (including the contributions of atmosphere, ocean, and hydrology) differ from the geodetic angular momentum excitation function (GAM). The former can simulate historical or forecast data based on the dynamic meteorological models with geodetic observations, while the latter can only get historical data through geodetic techniques such as global navigation satellite system (GNSS), very long baseline interferometry (VLBI), and satellite laser ranging (SLR). Because of potential observational errors and model deficiencies, gaps still exist between the two types of excitation functions in various timescale components. Thus, we must consider the effect of such gaps on the Earth orientation parameters (EOP) prediction. The key to further improving the prediction accuracy of EOP may rest in exploiting specific data processing approaches to address these gaps, so we conduct a detailed study on this issue. We analyze the differences and relations between the two types of excitation functions based on the Earth's rotation equation and its various timescale variational mechanisms. On this basis, we attempt to establish various matching schemes to reduce the gaps between the two types of excitation functions, exploit these schemes in the Earth's polar motion prediction, and compare the prediction results.
