Lagrangian Timescales of Southern Ocean Upwelling in a Hierarchy of Model Resolutions

TitleLagrangian Timescales of Southern Ocean Upwelling in a Hierarchy of Model Resolutions
Publication TypeJournal Article
Year of Publication2018
JournalGeophysical Research Letters
Volume48
Pages891-898
Date Published02/2018
Abstract / Summary

In this paper, we study upwelling pathways and timescales of Circumpolar Deep Water (CDW) in a hierarchy of models using a Lagrangian particle tracking method. Lagrangian timescales of CDW upwelling decrease from 87 years to 31 years to 17 years as the ocean resolution is refined from 1∘ to 0.25∘ to 0.1∘. We attribute some of the differences in timescale to the strength of the eddy fields, as demonstrated by temporally degrading high-resolution model velocity fields. Consistent with the timescale dependence, we find that an average Lagrangian particle completes 3.2 circumpolar loops in the 1∘ model in comparison to 0.9 loops in the 0.1∘ model. These differences suggest that advective timescales and thus interbasin merging of upwelling CDW may be overestimated by coarse-resolution models, potentially affecting the skill of centennial-scale climate change projections.

URLhttp://dx.doi.org/10.1002/2017gl076045
DOI10.1002/2017gl076045
Journal: Geophysical Research Letters
Year of Publication: 2018
Volume: 48
Pages: 891-898
Date Published: 02/2018

In this paper, we study upwelling pathways and timescales of Circumpolar Deep Water (CDW) in a hierarchy of models using a Lagrangian particle tracking method. Lagrangian timescales of CDW upwelling decrease from 87 years to 31 years to 17 years as the ocean resolution is refined from 1∘ to 0.25∘ to 0.1∘. We attribute some of the differences in timescale to the strength of the eddy fields, as demonstrated by temporally degrading high-resolution model velocity fields. Consistent with the timescale dependence, we find that an average Lagrangian particle completes 3.2 circumpolar loops in the 1∘ model in comparison to 0.9 loops in the 0.1∘ model. These differences suggest that advective timescales and thus interbasin merging of upwelling CDW may be overestimated by coarse-resolution models, potentially affecting the skill of centennial-scale climate change projections.

DOI: 10.1002/2017gl076045
Citation:
Drake, H, A Morrison, S Griffies, J Sarmiento, W Weijer, and A Gray.  2018.  "Lagrangian Timescales of Southern Ocean Upwelling in a Hierarchy of Model Resolutions."  Geophysical Research Letters 48: 891-898.  https://doi.org/10.1002/2017gl076045.