TY - JOUR
T1 - Roles of the Ocean Mesoscale in the Horizontal Supply of Mass, Heat, Carbon, and Nutrients to the Northern Hemisphere Subtropical Gyres
AU - Yamamoto, Ayako
AU - Palter, Jaime B.
AU - Dufour, Carolina O.
AU - Griffies, Stephen M.
AU - Bianchi, Daniele
AU - Claret, Mariona
AU - Dunne, John P.
AU - Frenger, Ivy
AU - Galbraith, Eric D.
PY - 2018/10/1
Y1 - 2018/10/1
N2 - ©2018. American Geophysical Union. All Rights Reserved. Horizontal transport at the boundaries of the subtropical gyres plays a crucial role in providing the nutrients that fuel gyre primary productivity, the heat that helps restratify the surface mixed layer, and the dissolved inorganic carbon that influences air-sea carbon exchange. Mesoscale eddies may be an important component of these horizontal transports; however, previous studies have not quantified the horizontal tracer transport due to eddies across the subtropical gyre boundaries. Here we assess the physical mechanisms that control the horizontal transport of mass, heat, nutrients, and carbon across the North Pacific and North Atlantic subtropical gyre boundaries using the eddy-rich ocean component of a climate model (Geophysical Fluid Dynamics Laboratory Climate Model version 2.6) coupled to a simple biogeochemical model (mini-BLING). Our results suggest that horizontal transport across the gyre boundaries supplies a substantial amount of mass and tracers to the ventilated layer of both Northern Hemisphere subtropical gyres, with the Kuroshio and Gulf Stream acting as main exchange gateways. Mass, heat, and dissolved inorganic carbon supply is principally driven by the time-mean circulation, whereas nutrient transport differs markedly from the other tracers, as nutrients are mainly supplied to both subtropical gyres by downgradient eddy mixing across gyre boundaries. A budget analysis further reveals that the horizontal nutrient transport, combining the roles of both mean and eddy components, is responsible for more than three quarters of the total nutrient supply into the subtropical gyres, surpassing a recent estimate based on a coarse-resolution model and thus further highlighting the importance of horizontal nutrient transport.
AB - ©2018. American Geophysical Union. All Rights Reserved. Horizontal transport at the boundaries of the subtropical gyres plays a crucial role in providing the nutrients that fuel gyre primary productivity, the heat that helps restratify the surface mixed layer, and the dissolved inorganic carbon that influences air-sea carbon exchange. Mesoscale eddies may be an important component of these horizontal transports; however, previous studies have not quantified the horizontal tracer transport due to eddies across the subtropical gyre boundaries. Here we assess the physical mechanisms that control the horizontal transport of mass, heat, nutrients, and carbon across the North Pacific and North Atlantic subtropical gyre boundaries using the eddy-rich ocean component of a climate model (Geophysical Fluid Dynamics Laboratory Climate Model version 2.6) coupled to a simple biogeochemical model (mini-BLING). Our results suggest that horizontal transport across the gyre boundaries supplies a substantial amount of mass and tracers to the ventilated layer of both Northern Hemisphere subtropical gyres, with the Kuroshio and Gulf Stream acting as main exchange gateways. Mass, heat, and dissolved inorganic carbon supply is principally driven by the time-mean circulation, whereas nutrient transport differs markedly from the other tracers, as nutrients are mainly supplied to both subtropical gyres by downgradient eddy mixing across gyre boundaries. A budget analysis further reveals that the horizontal nutrient transport, combining the roles of both mean and eddy components, is responsible for more than three quarters of the total nutrient supply into the subtropical gyres, surpassing a recent estimate based on a coarse-resolution model and thus further highlighting the importance of horizontal nutrient transport.
KW - circulation/dynamics
KW - lateral transport
KW - mesoscale eddies
KW - ocean tracers
KW - oceanic jet
KW - subtropical gyre
U2 - 10.1029/2018JC013969
DO - 10.1029/2018JC013969
M3 - Article
VL - 123
SP - 7016
EP - 7036
ER -