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A mass and energy conservation analysis of drift in the CMIP6 ensemble
Citation
Irving, D and Hobbs, W and Church, J and Zika, J, A mass and energy conservation analysis of drift in the CMIP6 ensemble, Journal of Climate pp. 1-43. ISSN 0894-8755 (2020) [Refereed Article]
Copyright Statement
© 2020 American Meteorological Society
DOI: doi:10.1175/JCLI-D-20-0281.1
Abstract
Coupled climate models are prone to ‘drift’ (long-term unforced trends in state variables) due to incomplete spin-up and non-closure of the global mass and energy budgets. Here we assess model drift and the associated conservation of energy, mass and salt in CMIP6 and CMIP5 models. For most models, drift in globally-integrated ocean mass and heat content represents a small but non-negligible fraction of recent historical trends, while drift in atmospheric water vapor is negligible. Model drift tends to be much larger in time-integrated ocean heat and freshwater flux, net top-of-the-atmosphere radiation (netTOA) and moisture flux into the atmosphere (evaporation minus precipitation), indicating a substantial leakage of mass and energy in the simulated climate system. Most models are able to achieve approximate energy budget closure after drift is removed, but ocean mass budget closure eludes a number of models even after de-drifting and none achieve closure of the atmospheric moisture budget. The magnitude of the drift in the CMIP6 ensemble represents an improvement over CMIP5 in some cases (salinity and time-integrated netTOA) but is worse (time-integrated ocean freshwater and atmospheric moisture fluxes) or little changed (ocean heat content, ocean mass and time-integrated ocean heat flux) for others, while closure of the ocean mass and energy budgets after drift removal has improved.
Item Details
Item Type: | Refereed Article |
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Keywords: | climate models, global energy balance |
Research Division: | Earth Sciences |
Research Group: | Oceanography |
Research Field: | Physical oceanography |
Objective Division: | Environmental Policy, Climate Change and Natural Hazards |
Objective Group: | Understanding climate change |
Objective Field: | Climate change models |
UTAS Author: | Hobbs, W (Dr Will Hobbs) |
ID Code: | 141507 |
Year Published: | 2020 |
Web of Science® Times Cited: | 1 |
Deposited By: | Oceans and Cryosphere |
Deposited On: | 2020-10-26 |
Last Modified: | 2021-01-27 |
Downloads: | 0 |
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