%0 Journal Article %1 ma2022potential %A Ma, Xiaofan %A Huang, Gang %A Li, Xichen %A Li, Shouwei %D 2022 %J Climate Dynamics %K moc-var %R 10.1007/s00382-022-06440-9 %T The potential mechanisms of the dominant timescale of AMOC multidecadal variability in CMIP6/CMIP5 preindustrial simulations %U https://doi.org/10.1007/s00382-022-06440-9 %X Observations, theoretical analyses, and climate models show that the dominant timescale of multidecadal variability of the Atlantic Meridional Overturning Circulation (AMOC) is related to westward temperature propagations in the subpolar North Atlantic, which is modulated by oceanic baroclinic Rossby waves or thermal Rossby waves. Here, we find major timescales of AMOC variability of 12--28 years and associated westward temperature propagations in the preindustrial simulations of 9 CMIP6/CMIP5 models. The comparison with observations shows that the models reasonably simulate ocean stratifications and baroclinic Rossby waves in the subpolar North Atlantic. The timescale of the oceanic baroclinic Rossby wave propagating on a static background across the basin overestimates the major timescale of AMOC variability. The dual effects of the mean flow on the AMOC timescale are then considered, involving the eastward advection and the additional westward propagation (i.e., thermal Rossby wave) induced by the northward mean potential vorticity gradient. We find that the AMOC major timescale is generally determined by the comprehensive effects of the baroclinic Rossby wave and the mean flow effects, in which the additional westward propagation plays a dominant role. Our results illustrate the importance of considering mean flow effects in the estimate of the dominant timescale of AMOC multidecadal variability.

@article{ma2022potential, abstract = {Observations, theoretical analyses, and climate models show that the dominant timescale of multidecadal variability of the Atlantic Meridional Overturning Circulation (AMOC) is related to westward temperature propagations in the subpolar North Atlantic, which is modulated by oceanic baroclinic Rossby waves or thermal Rossby waves. Here, we find major timescales of AMOC variability of 12--28 years and associated westward temperature propagations in the preindustrial simulations of 9 CMIP6/CMIP5 models. The comparison with observations shows that the models reasonably simulate ocean stratifications and baroclinic Rossby waves in the subpolar North Atlantic. The timescale of the oceanic baroclinic Rossby wave propagating on a static background across the basin overestimates the major timescale of AMOC variability. The dual effects of the mean flow on the AMOC timescale are then considered, involving the eastward advection and the additional westward propagation (i.e., thermal Rossby wave) induced by the northward mean potential vorticity gradient. We find that the AMOC major timescale is generally determined by the comprehensive effects of the baroclinic Rossby wave and the mean flow effects, in which the additional westward propagation plays a dominant role. Our results illustrate the importance of considering mean flow effects in the estimate of the dominant timescale of AMOC multidecadal variability.}, added-at = {2022-08-15T12:24:07.000+0200}, author = {Ma, Xiaofan and Huang, Gang and Li, Xichen and Li, Shouwei}, biburl = {https://www.bibsonomy.org/bibtex/2085871c03342a1ea2a07b96c99faa421/laura.jackson}, day = 09, description = {The potential mechanisms of the dominant timescale of AMOC multidecadal variability in CMIP6/CMIP5 preindustrial simulations | SpringerLink}, doi = {10.1007/s00382-022-06440-9}, interhash = {28a9818ccc58eda4d91fa21ea5cb869b}, intrahash = {085871c03342a1ea2a07b96c99faa421}, issn = {1432-0894}, journal = {Climate Dynamics}, keywords = {moc-var}, month = aug, timestamp = {2022-08-15T12:24:07.000+0200}, title = {The potential mechanisms of the dominant timescale of AMOC multidecadal variability in CMIP6/CMIP5 preindustrial simulations}, url = {https://doi.org/10.1007/s00382-022-06440-9}, year = 2022 }