Lagrangian pathways of upwelling in the Southern Ocean
- Creators
- Viglione, Giuliana A.
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Thompson, Andrew F.
Abstract
The spatial and temporal variability of upwelling into the mixed layer in the Southern Ocean is studied using a 1/10° ocean general circulation model. Virtual drifters are released in a regularly-spaced pattern across the Southern Ocean at depths of 250, 500, and 1000 m during both summer and winter months. The drifters are advected along isopycnals for a period of four years, unless they outcrop into the mixed layer, where lateral advection and a parameterization of vertical mixing is applied. The focus of this study is on the discrete exchange between the model mixed layer and the interior. Localization of interior-mixed layer exchange occurs downstream of major topographic features across the Indian and Pacific basins, creating "hotspots" of outcropping. Minimal outcropping occurs in the Atlantic basin, while 59% of drifters outcrop in the Pacific sector and in Drake Passage (the region from 140° W to 40° W), a disproportionately large amount even when considering the relative basin sizes. Due to spatial and temporal variations in mixed layer depth, the Lagrangian trajectories provide a statistical measure of mixed layer residence times. For each exchange into the mixed layer, the residence time has a Rayleigh distribution with a mean of 30 days; the cumulative residence time of the drifters is 261 ± 194 days, over a period of four years. These results suggest that certain oceanic gas concentrations, such as CO_2 and ^(14)C, will likely not reach equilibrium with the atmosphere before being re-subducted.
Additional Information
© 2016 American Geophysical Union. Received 4 MAR 2016; Accepted 4 AUG 2016; Accepted article online 8 AUG 2016; Published online 23 AUG 2016. We thank Jess Adkins, Matt Mazloff, and Jean-Baptiste Sallèe for helpful discussions during this work. AFT gratefully acknowledges support from the National Science Foundation (OCE-1235488). GAV thanks the Vanoni Fellowship for supporting this work. The model output used are listed in the references and available from JAMSTEC at http://www.jamstec.go.jp/esc/research/AtmOcn/product/ofes.html. The Argo-derived mixed layer depth data are available at http://apdrc.soest.hawaii.edu/datadoc/mld.php.Attached Files
Published - Viglione_et_al-2016-Journal_of_Geophysical_Research-_Oceans.pdf
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Additional details
- Eprint ID
- 69507
- Resolver ID
- CaltechAUTHORS:20160809-075333471
- NSF
- OCE-1235488
- Vanoni Fellowship
- Created
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2016-08-09Created from EPrint's datestamp field
- Updated
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2021-11-11Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences