Investigations of Modelled Earth Angular Momentum Data compared to Geodetic-Derived Momentum

In an ongoing effort to quantify performance of atmospheric and possibly additional momentum model results in support of better Earth Orientation Parameter forecasts, we compare Atmospheric (AAM) and possibly other Angular Momentum coefficients (c1, c2, and c3) to coefficients derived from geodetic sources.  The first derivative of UT1-UTC, or length of day (LOD), is proportional to the axial component of the dimensionless effective atmospheric angular momentum (AAM) functions (c3), given conservation of angular momentum in the Earth-atmosphere system.  Polar motion can also be derived from the c1 and c2 terms.  Earlier work by the same authors had compared AAM analysis files from results supplied by other meteorological centers.  This study will expand on the previous study to include additional systems and to include more data – specifically comparing AAM forecast data as well as the analysis files.  Various techniques to compare model accuracies are explored with the hope of gaining insight into how models might be improved in the future.