Dataset Information

Modeling ocean-induced rapid Earth rotation variations: an update.

ABSTRACT: 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 ∘ 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 ∘ 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.

SUBMITTER: Harker AA

PROVIDER: S-EPMC8550729 | biostudies-literature | 2021

REPOSITORIES: biostudies-literature

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Modeling ocean-induced rapid Earth rotation variations: an update.

Harker Alexander A AA Schindelegger Michael M Ponte Rui M RM Salstein David A DA

Journal of geodesy 20210907 9

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 ∘ 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 ser ...[more]

PMID: 34720453

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Project description:Abstract We describe the approach taken to develop the United Kingdom's first community Earth system model, UKESM1. This is a joint effort involving the Met Office and the Natural Environment Research Council (NERC), representing the U.K. academic community. We document our model development procedure and the subsequent U.K. submission to CMIP6, based on a traceable hierarchy of coupled physical and Earth system models. UKESM1 builds on the well?established, world?leading HadGEM models of the physical climate system and incorporates cutting?edge new representations of aerosols, atmospheric chemistry, terrestrial carbon, and nitrogen cycles and an advanced model of ocean biogeochemistry. A high?level metric of overall performance shows that both models, HadGEM3?GC3.1 and UKESM1, perform better than most other CMIP6 models so far submitted for a broad range of variables. We point to much more extensive evaluation performed in other papers in this special issue. The merits of not using any forced climate change simulations within our model development process are discussed. First results from HadGEM3?GC3.1 and UKESM1 include the emergent climate sensitivity (5.5 and 5.4?K, respectively) which is high relative to the current range of CMIP5 models. The role of cloud microphysics and cloud?aerosol interactions in driving the climate sensitivity, and the systematic approach taken to understand this role, is highlighted in other papers in this special issue. We place our findings within the broader modeling landscape indicating how our understanding of key processes driving higher sensitivity in the two U.K. models seems to align with results from a number of other CMIP6 models. Key Points The United Kingdom has developed its first community Earth system model and delivered a traceable hierarchy of models to CMIP6 We applied a process?based evaluation strategy in model development but chose not to use historic trends or measures of climate response The U.K. models exhibit higher climate sensitivity than seen in CMIP5 arising in part from more positive cloud feedbacks

Dataset Information

Modeling ocean-induced rapid Earth rotation variations: an update.

Publications

Modeling ocean-induced rapid Earth rotation variations: an update.

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