Using Atmosphere and Ocean Angular Momentum for Earth Orientation

The accuracy and robustness to input data outages of near real-time estimates and short-term predictions of Earth orientation parameters (EOPs) may be enhanced by using atmosphere and ocean angular momentum data accounting for the global conservation of angular momentum in the Earth system. The US Navy Earth System Prediction Capability (ESPC) data that combines the motion and mass fields of the atmosphere angular momentum information from the NAVY Global Environmental Model (NAVGEM 1.2) with that of the ocean angular momentum information from the HYbrid Coordinate Ocean Model (HYCOM) provides a source that can be used to evaluate the nature of the possible contribution of these physical data to the operational determination of the EOPs.  The rates of change of the EOPs derived from the most recent angular momentum data are evaluated in comparison with observed values of polar motion and UT1-UTC rates from the IERS RS/PC EOP data series, and the stability of statistical models accounting for systematic errors in scaling and bias in the ESPC data was investigated.  Analyses of these data show good agreement and indicate the viability of the practical integration of the rate data alone as well as in combination with data from other techniques in the operational determination of EOPs. Two years of past ESPC data were analyzed to provide estimates of the possible precision of the resulting polar motion and UT1-UTC data.