Meridional transport of salt in the global ocean from an eddy-resolving model
Meridional transport of salt in the global ocean from an eddy-resolving model
The meridional transport of salt is computed in a global eddy-resolving numerical model (1/12° resolution) in order to improve our understanding of the ocean salinity budget. A methodology is proposed that allows a global analysis of the salinity balance in relation to surface water fluxes, without defining a "freshwater anomaly" based on an arbitrary reference salinity. The method consists of a decomposition of the meridional transport into (i) the transport by the time–longitude–depth mean velocity, (ii) time–mean velocity recirculations and (iii) transient eddy perturbations. Water is added (rainfall and rivers) or removed (evaporation) at the ocean surface at different latitudes, which creates convergences and divergences of mass transport with maximum and minimum values close to ±1 Sv. The resulting meridional velocity effects a net transport of salt at each latitude (±30 Sv PSU), which is balanced by the time–mean recirculations and by the net effect of eddy salinity–velocity correlations. This balance ensures that the total meridional transport of salt is close to zero, a necessary condition for maintaining a quasi-stationary salinity distribution. Our model confirms that the eddy salt transport cannot be neglected: it is comparable to the transport by the time–mean recirculation (up to 15 Sv PSU) at the poleward and equatorial boundaries of the subtropical gyres. Two different mechanisms are found: eddy contributions are localized in intense currents such as the Kuroshio at the poleward boundary of the subtropical gyres, while they are distributed across the basins at the equatorward boundaries. Closer to the Equator, salinity–velocity correlations are mainly due to the seasonal cycle and large-scale perturbations such as tropical instability waves.
243-255
Treguier, A.M.
bb921a5f-42da-4c8c-9d0b-1af3b5254a33
Deshayes, J.
4d1c9d33-bf58-447d-a519-e6ccf27f1f3a
Le Sommer, J.
b2f7856c-9030-4d9e-bda6-dbfea753d329
Lique, C.
9a6813af-05b0-4a6a-815e-777afb24acfd
Madec, G.
7e2ec04b-896a-4861-b2d0-b74f39d748c2
Penduff, T.
acc9246c-9cec-4909-814f-ec3eefa7f11d
Molines, J.-M.
1f4c8833-7bd7-4298-b259-1a0712283734
Barnier, B.
0179fa7c-ed1b-45df-9e81-5a959268d99b
Bourdalle-Badie, R.
c26e0a88-ee1a-4afa-8bbd-7cfda932e50f
Talandier, C.
e3c52f12-4ced-42d3-add5-7b74e23bc915
17 April 2014
Treguier, A.M.
bb921a5f-42da-4c8c-9d0b-1af3b5254a33
Deshayes, J.
4d1c9d33-bf58-447d-a519-e6ccf27f1f3a
Le Sommer, J.
b2f7856c-9030-4d9e-bda6-dbfea753d329
Lique, C.
9a6813af-05b0-4a6a-815e-777afb24acfd
Madec, G.
7e2ec04b-896a-4861-b2d0-b74f39d748c2
Penduff, T.
acc9246c-9cec-4909-814f-ec3eefa7f11d
Molines, J.-M.
1f4c8833-7bd7-4298-b259-1a0712283734
Barnier, B.
0179fa7c-ed1b-45df-9e81-5a959268d99b
Bourdalle-Badie, R.
c26e0a88-ee1a-4afa-8bbd-7cfda932e50f
Talandier, C.
e3c52f12-4ced-42d3-add5-7b74e23bc915
Treguier, A.M., Deshayes, J., Le Sommer, J., Lique, C., Madec, G., Penduff, T., Molines, J.-M., Barnier, B., Bourdalle-Badie, R. and Talandier, C.
(2014)
Meridional transport of salt in the global ocean from an eddy-resolving model.
Ocean Science, 10 (2), .
(doi:10.5194/os-10-243-2014).
Abstract
The meridional transport of salt is computed in a global eddy-resolving numerical model (1/12° resolution) in order to improve our understanding of the ocean salinity budget. A methodology is proposed that allows a global analysis of the salinity balance in relation to surface water fluxes, without defining a "freshwater anomaly" based on an arbitrary reference salinity. The method consists of a decomposition of the meridional transport into (i) the transport by the time–longitude–depth mean velocity, (ii) time–mean velocity recirculations and (iii) transient eddy perturbations. Water is added (rainfall and rivers) or removed (evaporation) at the ocean surface at different latitudes, which creates convergences and divergences of mass transport with maximum and minimum values close to ±1 Sv. The resulting meridional velocity effects a net transport of salt at each latitude (±30 Sv PSU), which is balanced by the time–mean recirculations and by the net effect of eddy salinity–velocity correlations. This balance ensures that the total meridional transport of salt is close to zero, a necessary condition for maintaining a quasi-stationary salinity distribution. Our model confirms that the eddy salt transport cannot be neglected: it is comparable to the transport by the time–mean recirculation (up to 15 Sv PSU) at the poleward and equatorial boundaries of the subtropical gyres. Two different mechanisms are found: eddy contributions are localized in intense currents such as the Kuroshio at the poleward boundary of the subtropical gyres, while they are distributed across the basins at the equatorward boundaries. Closer to the Equator, salinity–velocity correlations are mainly due to the seasonal cycle and large-scale perturbations such as tropical instability waves.
Text
os-10-243-2014.pdf
- Version of Record
More information
Published date: 17 April 2014
Organisations:
Marine Systems Modelling
Identifiers
Local EPrints ID: 365540
URI: http://eprints.soton.ac.uk/id/eprint/365540
ISSN: 1812-0792
PURE UUID: 341611ef-b6de-4cc2-bf21-165c6fbbac87
Catalogue record
Date deposited: 09 Jun 2014 13:47
Last modified: 14 Mar 2024 16:57
Export record
Altmetrics
Contributors
Author:
A.M. Treguier
Author:
J. Deshayes
Author:
J. Le Sommer
Author:
C. Lique
Author:
G. Madec
Author:
T. Penduff
Author:
J.-M. Molines
Author:
B. Barnier
Author:
R. Bourdalle-Badie
Author:
C. Talandier
Download statistics
Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.
View more statistics