Transport of Freshwater by the Oceans

Wijffels, Susan E.; Schmitt, Raymond W.; Bryden, Harry L.; Stigebrandt, Anders

doi:10.1175/1520-0485(1992)022<0155:tofbto>2.0.co;2

Cited by 241 publications

(176 citation statements)

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“…The salt transports in the present rigid-lid model can be converted to equivalent freshwater transports by dividing by a factor of -0.035. The results compare fairly closely to the freshwater flux deduced from the atmospheric water cycle by Wijffels et al [1992]. Further discussion is given by McCann et al (1992).…”

supporting

confidence: 82%

Ocean general circulation from a global eddy‐resolving model

Semtner¹,

Chervin²

1992

J. Geophys. Res.

462

186

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A concerted effort has been made to simulate the global ocean circulation with resolved eddies, using a highly optimized model on the best available supercomputer. An earlier 20-year spin-up has been extended for 12.5 additional years: the first 2.5 with continued annual mean forcing and the final 10.0 with climatological monthly forcing. Model output archived at 3-day intervals has been analyzed into mean fields, standard deviations, products, and covariances on monthly, annual, and multiyear time scales. The multiyear results are examined here in order to give insight into the general circulation of the world ocean. The three-dimensional How fields of the model are quite realistic, even though resolution of eddies in high latitudes is marginal with a 0.5°, 20-level grid. The use of seasonal forcing improves the simulation, especially in the tropics and high northern latitudes. Mid-latitude gyre circulations, western boundary currents, zonal equatorial Hows, and the Antarctic Circumpolar Current (ACC) all show mean and eddy characteristics similar to those observed. There is also some indication of eddy intensification of the mean How of the ACC and of separated boundary jets. A global thermohaline circulation of North Atlantic Deep Water is identified in deep western boundary currents connected by the ACC. This deep circulation rises mainly in the equatorial Pacific. Several zonal jets are an integral part of this circulation near the equator. The deep How rises toward the surface in a series of switchbacks. Much of the thermohaline return How then follows an eddy-rich warm-water route through the Indonesian archipelago and around the southern tip of Africa. However, some intermediate level portions of the thermohaline circulation return south into the ACC and follow a cold water route through the Drake Passage. The representation of a global "conveyor belt" circulation with narrow and relatively high-speed currents along most of its path may be the most important result of this modeling study. Statistics of scalar fields such as transport stream function and surface height are exhibited, as are time series and frequency spectra of certain variables at selected points. These provide a baseline for comparison both with observations and with other model studies at higher resolution. Mean and eddy characteristics of the near-surface temperature and salinity fields are discussed, and surface forcing fields are examined. In particular, combined thermal and hydrological forcing effects are found to drive a conveyor belt circulation between the tropical Pacific and the high-latitude North Atlantic. The effect of weak restoring terms to observed temperature and salinity at great depth and in polar latitudes is found mainly to augment the model's convective processes, which are poorly resolved with 0.5° grid spacing. However, the deep restoring terms are insignificant in both the tropics and the mid-latitudes. The geographical distributions of eddy heat and salt transport are discussed. The eddies transport heat and sa...

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supporting

confidence: 82%

Ocean general circulation from a global eddy‐resolving model

Semtner¹,

Chervin²

1992

J. Geophys. Res.

462

186

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“…The heat transport at 24.5 • N has been estimated several times in previous studies, especially for the 1992 realization; for instance, Ganachaud and Wunsch (2003) in 1989 and 2013, respectively. This is the first freshwater transport estimation at 14.5 • N based on hydrographic data; compared to the estimates based on surface freshwater transport (i.e., integrating the evaporation, precipitation, and river runoff from a northern latitude with initial conditions; Wijffels et al, 1992), it is somewhat larger. However, given a net surface freshwater loss of about 0.3 Sv between 24.5 and 14.5 • N estimated using the Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data (HOAPS) and −1.17 ± 0.20 Sv as the initial condition at 24.5 • N, the estimates at 14.5 • N are still within the uncertainty range.…”

Section: Heat and Freshwater Transportsmentioning

confidence: 87%

Atlantic Meridional Overturning Circulation at 14.5° N in 1989 and 2013 and 24.5° N in 1992 and 2015: volume, heat, and freshwater transports

Karstensen

Brandt

2018

Ocean Sci.

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“…Large-scale observation based studies (including inverse solutions) reveal significant Pacific export of freshwater and heat into the Indian Ocean (Piola and Gordon, 1984;Toole and Raymer, 1985;Wijffels et al, 1992;Macdonald, 1993;Toole and Warren, 1993;Macdonald and Wunsch, 1996;Robbins and Toole, 1997;. Increased oceanic heat and freshwater flux into the Indian Ocean at the expense of the Pacific affects atmosphere-ocean coupling with potential impacts on the ENSO and monsoon phenomena.…”

Section: Introductionmentioning

confidence: 99%

The heat transport of the Indonesian Throughflow and implications for the Indian Ocean heat budget

Vranes

Gordon

Ffield

2002

Deep Sea Research Part II: Topical Studies in Oceanography

122

103

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The Indonesian Throughflow (ITF) is considered central to the heat budgets of the Pacific and Indian Oceans. Temperature and ocean current time series obtained within the Makassar Strait from December 1996 to early July 1998 are used to calculate heat transport of the ITF and assess its influence on Indian Ocean heat divergence. Velocity and temperature values for the surface layer that were not directly measured are extrapolated from the shallowest measurement to the sea surface using a variety of model profiles. While a single temperature profile is used based on a linear interpolation from NCEP OI sea-surface temperatures to the top-most mooring temperature recorder, four different velocity profiles are employed. Heat transport is calculated as volume transport multiplied by temperature, density and specific heat, using reference temperatures between 01C and 41C. The mean heat transport averages 0.55 PW relative to 01C, and 0.41 PW relative to 41C for the two most reasonable velocity profiles. In comparison, model heat transport values are larger, between 0.6 and 1.15 PW. Heat transport varies with ENSO phase, lower during El Ni * no, higher during La Ni * na. As 1997 was a strong El Ni * no year, our heat transport estimate may be less than the climatic mean. The ITF water is advected towards Africa within the Indian Ocean South Equatorial Current, to eventually exit the Indian Ocean across 301S, most likely within the Agulhas Current. For realistic consideration of the ITF component within the Agulhas Current, the heat flux divergence of ITF waters within the Indian Ocean north of 301S is found to be insignificant. Our results provide support for model studies and hydrographic geostrophic inverse calculations that indicate the ITF heat, derived from the Pacific Ocean, is ultimately lost to the atmosphere in the southwest Indian Ocean. r

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Transport of Freshwater by the Oceans

Cited by 241 publications

References 0 publications

Ocean general circulation from a global eddy‐resolving model

Ocean general circulation from a global eddy‐resolving model

Atlantic Meridional Overturning Circulation at 14.5° N in 1989 and 2013 and 24.5° N in 1992 and 2015: volume, heat, and freshwater transports

The heat transport of the Indonesian Throughflow and implications for the Indian Ocean heat budget

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