FN Archimer Export Format
PT J
TI First direct estimates of volume and water mass transports across the Reykjanes Ridge
BT 
AF PETIT, Tillys
   MERCIER, Herle
   THIERRY, Virginie
AS 1:1;2:2;3:1;
FF 1:PDG-ODE-LOPS-OH;2:;3:PDG-ODE-LOPS-OH;
C1 Univ Brest, LOPS, IUEM, CNRS,IRD,Ifremer, Brest, France.
C2 IFREMER, FRANCE
   CNRS, FRANCE
SI BREST
SE PDG-ODE-LOPS-OH
UM LOPS
IN WOS Ifremer jusqu'en 2018
   copubli-france
IF 3.235
TC 19
UR https://archimer.ifremer.fr/doc/00454/56604/58296.pdf
LA English
DT Article
CR RREX 2015
BO Thalassa
DE ;North Atlantic subpolar gyre;bathymetry;water masses;circulation;observations
AB The Reykjanes Ridge is a major topographic feature located south of Iceland in the North‐Atlantic Ocean that strongly influences the subpolar gyre (SPG) circulation. Based on velocity and hydrographic measurements carried out along the crest of the Reykjanes Ridge from the Icelandic continental shelf to 50°N during the RREX cruise in June – July 2015, we derived the first direct estimates of volume and water mass transports over the Reykjanes Ridge. North of 53.15°N, circulation was mainly westward; south of this latitude it was mainly eastward. The westward transport was estimated at 21.9 ± 2.5 Sv (Sv = 106 m3 s‐1) and represents the SPG intensity. The westward flows followed two main pathways at 57°N near the Bight Fracture Zone and at 59 – 62°N. We argue that those pathways were connected to the northern branch of the North Atlantic Current and to the Sub‐Arctic Front respectively, which were both intersected by the southern part of the section. In addition to this horizontal circulation, mixing and bathymetry shaped the water mass distribution. Water mass transformations in the Iceland Basin lead to the formation of weakly stratified SubPolar Mode Water (SPMW). We explain why SPMW, the main water mass contributing to the westward flow, was denser at 57°N than at 59 – 62°N. At higher densities, both Intermediate Water and Icelandic Slope Water contributed more to the westward transport across the Reykjanes Ridge than the sum of Labrador Sea Water and Iceland‐Scotland Overflow Water. Plain Language Summary The Reykjanes Ridge, the northern section of the Mid‐Atlantic Ridge, strongly influences the cyclonic circulation of the North‐Atlantic subpolar gyre, a major component of the climate system. Up to now, no dedicated dataset was available to describe the circulation across this ridge. To fill this gap, surface‐to‐bottom measurements of flow velocity and water mass properties were carried out along the crest of the ridge, from Iceland to 50{degree sign}N, in 2015. North of 53.15{degree sign}N, the flow was mainly westward. It defines the westward branch of the subpolar gyre and our study provides the first direct estimate of its intensity. The westward flow followed two main pathways related to specific bathymetry features: at the Bight Fracture Zone (57{degree sign}N), which is a deep opening in the ridge, and at 59 ‐ 62{degree sign}N where the bathymetry rapidly deepens southward. The horizontal circulation of the Iceland Basin connects these pathways to the North‐Atlantic Current flowing eastward south of 53.15{degree sign}N. Knowledge of the westward cross‐ridge flows is a prerequisite for understanding the northward evolution of the Irminger Current, a major conduit for the subtropical waters towards the deep convection regions in the Irminger and Labrador Seas. 
PY 2018
PD SEP
SO Journal Of Geophysical Research-oceans
SN 2169-9275
PU Amer Geophysical Union
VL 123
IS 9
UT 000447552600039
BP 6703
EP 6719
DI 10.1029/2018JC013999
ID 56604
ER

EF