Oceanic Effects on Earth Rotational Change: A Case Study with Satellite Altimetry and Data Assimilating OGCM

We compute oceanic contributions to polar motion and length-of-day (LOD) variation using non-steric sea level change derived from TOPEX/Poseidon satellite radar altimeter observations over a 9 years' period (1993 - 2001) and outputs from a data assimilating ocean general circulation model (OGCM). Both the altimeter derived oceanic mass variations and the data assimilating OGCM estimates indicates that the oceans play an important role in driving the Earth rotational change, especially in polar motion and at intraseasonal time scales. The results from this study show considerable improvement in the agreement between observed polar motion and LOD excitations (after atmospheric effects are removed) and contributions from the ocean when compared with previous studies.