Publication Date:
2023-06-22
Description:
We revisit the problem of modeling the ocean’s contribution to rapid, non-tidal Earth rotation variations at periods of 2–120 days. Estimates of oceanic angular momentum (OAM, 2007–2011) are drawn from a suite of established circulation models and new numerical simulations, whose finest configuration is on a 1⁄ 6◦ grid. We show that the OAM product by the Earth System Modeling Group at GeoForschungsZentrum Potsdam has spurious short period variance in its equatorial motion terms, rendering the series a poor choice for describing oceanic signals in polar motion on time scales of less than ∼2 weeks. Accounting for OAM in rotation budgets from other models typically reduces the variance of atmosphere-corrected geodetic excitation by ∼54% for deconvolved polar motion and by ∼60% for length-of-day. Use of OAM from the 1⁄ 6◦ model does provide for an additional reduction in residual variance such that the combined oceanic–atmospheric effect explains as much as 84% of the polar motion excitation at periods 〈 120 days. Employing statistical analysis and bottom pressure changes from daily Gravity Recovery and Climate Experiment solutions, we highlight the tendency of ocean models run at a 1◦ grid spacing to misrepresent topographically constrained dynamics in some deep basins of the Southern Ocean, which has adverse effects on OAM estimates taken along the 90◦ meridian. Higher model resolution thus emerges as a sensible target for improving the oceanic component in broader efforts of Earth system modeling for geodetic purposes.
Description:
Austrian Science Fund
http://dx.doi.org/10.13039/501100002428
Description:
National Aeronautics and Space Administration
http://dx.doi.org/10.13039/100000104
Description:
https://isdc.gfz-potsdam.de/ggfc-oceans/
Description:
https://doi.org/10.5281/zenodo.4707150
Description:
http://rz-vm115.gfz-potsdam.de:8080/repository/
Description:
https://ifg.tugraz.at/ITSG-Grace2018
Description:
ftp://isdcftp.gfz-potsdam.de/grace/Level-1B/GFZ/AOD/RL06/
Description:
https://ecco-group.org/products-ECCO-V4r4.htm
Keywords:
ddc:550.2
;
Earth rotation
;
Geophysical fluids
;
Excitation
;
Ocean bottom pressure
Language:
English
Type:
doc-type:article
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