FN Archimer Export Format
PT J
TI Observing the Local Emergence of the Southern Ocean Residual-Mean Circulation
BT 
AF Sévellec, Florian
   NAVEIRA GARABATO, A
   Vic, Clement
   Ducousso, N.
AS 1:1,2;2:2;3:2;4:1;
FF 1:;2:;3:;4:;
C1 Laboratoire d'Océanographie Physique et Spatiale, CNRS Univ.-Brest IRD Ifremer; Brest France
   Ocean and Earth Science, University of Southampton; Southampton UK
C2 CNRS, FRANCE
   UNIV SOUTHAMPTON, UK
UM LOPS
IN WOS Cotutelle UMR
   copubli-europe
IF 4.497
TC 2
UR https://archimer.ifremer.fr/doc/00485/59655/62687.pdf
   https://archimer.ifremer.fr/doc/00485/59655/62688.pdf
   https://archimer.ifremer.fr/doc/00485/59655/62689.tex
LA English
DT Article
DE ;Southern Ocean;meridional overturning;mesoscale turbulence;residual-mean circulation;Eulerian circulation;mooring measurements
AB The role of mesoscale turbulence in maintaining the mean buoyancy structure and overturning circulation of the Southern Ocean is investigated through a 2‐year‐long, single‐mooring record of measurements in Drake Passage. The buoyancy budget of the area is successively assessed within the Eulerian and the Temporal‐Residual‐Mean frameworks. We find that a regime change occurs on timescales of 1 day to 100 days, characteristic of mesoscale dynamics, whereby the eddy‐induced turbulent horizontal advection balances the vertical buoyancy advection by the mean flow. We use these diagnostics to reconstruct the region's overturning circulation, which is found to entail an equatorward downwelling of Antarctic Intermediate and Bottom Waters and a poleward upwelling of Circumpolar Deep Water. The estimated eddy‐induced flow can be accurately parameterized via the Gent‐McWilliams closure by adopting a diffusivity of ~2,000 m2 s‐1 with a mid‐depth increase to 2,500 m2 s‐1 at 2,100 m, immediately underneath the maximum interior stratification. Plain Language Summary In this study we use a 2‐yr long, high‐resolution (both temporally and vertically) mooring together with a state‐of‐the‐art method (Temporal‐Residual‐Mean framework) to disentangle the role of mesoscale eddy turbulence for sustaining the Meridional Overturning Circulation leeward of the Drake Passage.Because of its role in carbon sequestration and ocean heat uptake the Meridional Overturning Circulation is a key component of the climate system. However, it is driven by a wide range of physical processes from persistent, large‐scale wind to meso‐ and small‐scale turbulence. Hence disentangling how these processes contribute to the maintenance of this climatically relevant ocean circulation is one of the current challenges in physical oceanography. Here we apply a state‐of‐the‐art method (Temporal‐Residual‐Mean framework) and shows the emergence of a balance between mesoscale eddies and Eulerian mean circulation for buoyancy advection. In particular, we demonstrate that the effect mesoscale eddies can be accurately parameterized with a Gent‐McWilliams type diffusivity of ~2,000 m2 s‐1. Beyond this result, this study also provides an observational evidence of the typical large‐scale picture of the Meridional Overturning Circulation and shows its relevance at local scales. 
PY 2019
PD APR
SO Geophysical Research Letters
SN 0094-8276
PU American Geophysical Union (AGU)
VL 46
IS 7
UT 000465836200031
BP 3862
EP 3870
DI 10.1029/2018GL081382
ID 59655
ER

EF