Disentangling Climatic Signals in Earth Orientation Parameters

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A project placed at the interface of geodesy and physical Earth system science is proposed which will attack outstanding problems in Earth rotation research. The central objective is to unravel the signatures of three leading modes of climate system variability on time scales from a few weeks to several years in geodetically observed polar motion and length-of-day changes. The project specifically addresses the Madden-Julian Oscillation, the Southern Annular Mode, and the El Niño–Southern Oscillation, as diagnosed from five modern global atmospheric reanalyses, three unconstrained ocean forward models, and a global ocean state estimate, with surface mass changes derived from satellite gravimetry observations. Chosen datasets and numerical experiments reflect both the pursuit for accurate, kinematically consistent depictions of mass redistribution in geophysical fluids and the requirement for uncertainty estimates of atmosphere-ocean angular momentum series across a wide range of time scales. A core set of ocean forward simulations will be paired with existing, multi-decadal atmospheric reanalyses and provided as global angular momentum estimates to the international community to stimulate new research on other important geophysical signals in Earth Orientation Parameters.