Impacts of meso- to submeso-scale features on the ocean circulation in the Coral Sea
Impacts of meso- to submeso-scale features on the ocean circulation in the Coral Sea
Abstract:
As part of the South Pacific subtropical gyre, the encounter of the South Equatorial Current (SEC)
with the complex bottom topography and numerous islands of the southwest tropical Pacific results
into a series of zonal jets, flowing mainly westward off the tip of archipelagos. Moreover, the
mesoscale activity at basin scale is dominated by westward-propagating nonlinear eddies, with a
strong impact on the ocean circulation, the mixing of water masses and tracers' distribution. Eddyjet
interactions are studied here with the data collected in September 2012 during the
BIFURCATION cruise in the Coral Sea, under the auspices of SPICE (Southwest PacIfic Ocean
Circulation and Climate Experiment). We analyze and explain in situ data with the help of satellitebased
remote sensing data (altimetry, SSS, SST, ocean color), and we estimate the mass transport
budget within the Coral Sea. We show that the mesoscale activity is a significant contributor to the
0-600m transport estimates (5-10 Sv) and is essential for the interpretation of hydrological
observations. A specific mesoscale eddy is identified as responsible for the connection between the
North Vanuatu Jet (NVJ) and the North Caledonian Jet (NCJ). By using a Lagrangian technique, we
are able to confirm the long-term connection between the NVJ and the NCJ through mesoscale
activity. At a smaller scale, our analysis shows that surface temperature and salinity gradients can be
associated with hydrodynamical submesoscale features depicted by Finite Size Lyapunov
Exponents (FSLE). These structures can also be linked to the presence of diazotroph species, in
contrast with the general oligotrophy of the area. This study offers interesting outlooks for the use
of FSLE to study the distribution of biogeochemical elements.
with the complex bottom topography and numerous islands of the southwest tropical Pacific results
into a series of zonal jets, flowing mainly westward off the tip of archipelagos. Moreover, the
mesoscale activity at basin scale is dominated by westward-propagating nonlinear eddies, with a
strong impact on the ocean circulation, the mixing of water masses and tracers' distribution. Eddyjet
interactions are studied here with the data collected in September 2012 during the
BIFURCATION cruise in the Coral Sea, under the auspices of SPICE (Southwest PacIfic Ocean
Circulation and Climate Experiment). We analyze and explain in situ data with the help of satellitebased
remote sensing data (altimetry, SSS, SST, ocean color), and we estimate the mass transport
budget within the Coral Sea. We show that the mesoscale activity is a significant contributor to the
0-600m transport estimates (5-10 Sv) and is essential for the interpretation of hydrological
observations. A specific mesoscale eddy is identified as responsible for the connection between the
North Vanuatu Jet (NVJ) and the North Caledonian Jet (NCJ). By using a Lagrangian technique, we
are able to confirm the long-term connection between the NVJ and the NCJ through mesoscale
activity. At a smaller scale, our analysis shows that surface temperature and salinity gradients can be
associated with hydrodynamical submesoscale features depicted by Finite Size Lyapunov
Exponents (FSLE). These structures can also be linked to the presence of diazotroph species, in
contrast with the general oligotrophy of the area. This study offers interesting outlooks for the use
of FSLE to study the distribution of biogeochemical elements.