Motion of the Earth's pole of rotation relative to its crust, commonly referred to as polar motion, can be excited by a variety of geophysical mechanisms1. In particular, changes in atmospheric wind and mass fields have been linked to polar motion over a wide range of timescales, but substantial discrepancies remain between the atmospheric and geodetic observations1,2,3,4. Here we present results from a nearly global ocean model which indicate that oceanic circulation and mass-field variability play important roles in the excitation of seasonal to fortnightly polar motion. The joint oceanic and atmospheric excitation provides a better agreement with the observed polar motion than atmospheric excitation alone. Geodetic measurements may therefore be used to provide a global consistency check on the quality of simulated large-scale oceanic fields.
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We thank D. Spiegel for help with the computation, and F. Bryan, B. Chao, R. Rosen and D. Salstein for comments. This work was supported by NASA's Mission to Planet Earth.
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Journal of Geodesy (2019)
Geophysical Journal International (2019)
Acta Geophysica (2019)
Science China Earth Sciences (2018)