Viglione, Giuliana A. and Thompson, Andrew F. (2016) Lagrangian pathways of upwelling in the Southern Ocean. Journal of Geophysical Research. Oceans, 121 (8). pp. 6295-6309. ISSN 2169-9275. http://resolver.caltech.edu/CaltechAUTHORS:20160809-075333471
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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.|
|Subject Keywords:||Southern Ocean; upwelling; Lagrangian pathways; mixed layer|
|Official Citation:||Viglione, G. A., and A. F. Thompson (2016), Lagrangian pathways of upwelling in the Southern Ocean, J. Geophys. Res. Oceans, 121, 6295–6309, doi:10.1002/2016JC011773|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||09 Aug 2016 15:59|
|Last Modified:||02 Feb 2017 18:26|
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