FN Archimer Export Format
PT J
TI Vertical Interaction Between NBC Rings and Its Implications for South Atlantic Water Export
BT 
AF Napolitano, Dante C.
   Carton, Xavier
   Gula, Jonathan
AS 1:1;2:1;3:1,2;
FF 1:;2:;3:;
C1 Laboratoire d’Océanographie Physique et Spatiale (LOPS) Univ Brest CNRS Ifremer IRD IUEM Plouzané, France
   Institut Universitaire de France (IUF) Paris, France
C2 UBO, FRANCE
   INST UNIV FRANCE, FRANCE
UM LOPS
IN WOS Cotutelle UMR
   copubli-france
IF 3.6
TC 0
UR https://archimer.ifremer.fr/doc/00884/99620/109632.pdf
   https://archimer.ifremer.fr/doc/00884/99620/109633.pdf
   https://archimer.ifremer.fr/doc/00884/99620/109635.mp4
LA English
DT Article
CR EUREC4A_OA
BO L'Atalante
DE ;NBC rings;South Atlantic Water;vertical coupling;eddy alignment;North Brazil Current;eddy tracking
AB Northwestward‐propagating North Brazil Current (NBC) Rings are often destroyed upon reaching the Caribbean islands, carrying South Atlantic waters into the North Atlantic gyre and connecting the two branches of the Atlantic Meridional Overturning Circulation. Recent observations of NBC rings reported surface and subsurface cores separated by strong stratification. As independent structures, the subsurface eddies often appeared below—even if not aligned with—the surface rings. Motivated by these findings, this paper investigates the occurrence and consequences of vertical coupling between surface and subsurface NBC rings by applying a simplified theoretical model to a realistic numerical simulation. Eddy tracking in this complex simulation reveals around 1,600 instantaneous observations where eddies overlap. At each observation, we assess the eddies' vertical interaction with a 21/2‐layer quasi‐geostrophic framework. This interaction boils down to either coupling between the layers or a vertical splitting of the system, depending on eddy strength versus background shear. The effects of coupling include long‐lived eddies that can travel longer distances. These effects are particularly important for the lower layer, where differences between coupled and non‐coupled eddies are striking: about 40% of eddies with coupling travel 500 km, with ∼10% carrying South Atlantic Water up to the Caribbean sea. Without coupling, eddies propagate less than 150 km. During coupling, lower‐layer eddies could be driven by their surface counterparts to move offshore and bypass a topographic choke point, thus leaving the NBC retroflection region. Although still speculative, this idea explains the link between coupling and the increase in both lifetime and distance traveled for these eddies. 
PY 2024
PD APR
SO Journal Of Geophysical Research-oceans
SN 2169-9275
PU American Geophysical Union (AGU)
VL 129
IS 4
UT 001191110500001
DI 10.1029/2023JC020741
ID 99620
ER

EF