Expected Seasonal Excitations of Earth Rotation by Unmodeled Geophysical Fluids


We compare modeled (atmospheric and oceanic) seasonal excitations of the Earth rotation with the observed ones and estimate expected seasonal excitations from unmodeled geophysical fluids, primarily attributable to the hydrologic excitations. Through budget analysis of the seasonal excitations, maximum deficits in geophysical excitations occur in boreal spring to summer. If we assume a mass source on the Earth to compensate the deficits, a positive mass excess is expected around longitudes 90°E to 120°E or from 60°W to 90°W. Observation of the Earth rotation is useful for constraining geophysical excitations with some errors. The interannual variability in seasonal excitations also affects the estimation of Chandler parameters.


1. Introduction
2. Data sets and methods
3. Observed and modeled seasonal excitations
4. Expected hydrological excitations through budget analysis
5. Effects on estimation of the Chandler parameters with varying seasonal signals
6. Discussion
7. Conclusion