Oceanography The Official Magazine of
The Oceanography Society
Volume 28 Issue 01

View Issue TOC
Volume 28, No. 1
Pages 40 - 45


A River of Salt

By Raymond W. Schmitt  and Austen Blair  
Jump to
Article Abstract Citation References Copyright & Usage
Article Abstract

Terrestrial rivers are a well-known part of the global water cycle, and there has been recent discussion of “atmospheric rivers” that transport vast quantities of moisture from the tropical ocean to mid-latitudes in transient weather systems. Complementary “salt rivers” within the ocean are an equally important part of the global water cycle. They help define the ocean’s methods of returning water to where it is needed to maintain sea level and the global water cycle. One part of the Salinity Processes in the Upper-ocean Regional Study (SPURS) focused on the North Atlantic surface salinity maximum, where high evaporation rates remove freshwater from the ocean surface and leave dissolved salts behind. Much of the effort is devoted to understanding how that salty water disperses through lateral and vertical mixing processes. One important exit path is simple advection within the general circulation, which in the central Atlantic means the wind-driven “Sverdrup” circulation. Evaporation results in high salinity within the flow, marking a subsurface salt river within the ocean. Here, we examine the river’s structure as revealed in the average salinity field of the North Atlantic. Mid-ocean salinity maxima provide a unique opportunity to use an isohaline control volume approach for analyzing the mixing processes that disperse the high-salinity plume.


Schmitt, R.W., and A. Blair. 2015. A river of salt. Oceanography 28(1):40–45, https://doi.org/10.5670/oceanog.2015.04.


Abernathey, R.P., and J. Marshall. 2013. Global surface eddy diffusivities derived from satellite altimetry. Journal of Geophysical Research 118:901–916, https://doi.org/10.1002/jgrc.20066.

Bauer, E., and G. Siedler. 1988. The relative contributions of advection and isopycnal and diapycnal mixing below the subtropical salinity maximum. Deep Sea Research Part A 35:811–837, https://doi.org/10.1016/0198-0149(88)90032-5.

Dohan, K., H.-Y. Kao, and G.S.E. Lagerloef. 2015. The freshwater balance over the North Atlantic SPURS domain from Aquarius satellite salinity, OSCAR satellite surface currents, and some simplified approaches. Oceanography 28(1):86–95, https://doi.org/10.5670/oceanog.2015.07.

Durack, P.J., and S.E. Wijffels. 2010. Fifty-year trends in global ocean salinities and their relationship to broad-scale warming. Journal of Climate 23:4,342–4,362, https://doi.org/10.1175/2010JCLI3377.1.

Durack, P.J., S.E. Wijffels, and R.J. Matear. 2012. Ocean salinities reveal strong global water cycle intensification during 1950 to 2000. Science 336:455–458, https://doi.org/10.1126/science.1212222.

Farrar, J.T., L. Rainville, A.J. Plueddemann, W.S. Kessler, C. Lee, B.A. Hodges, R.W. Schmitt, J.B. Edson, S.C. Riser, C.C. Eriksen, and D.M. Fratantoni. 2015. Salinity and temperature balances at the SPURS central mooring during fall and winter. Oceanography 28(1):56–65, https://doi.org/10.5670/oceanog.2015.06.

Gordon, A.L., and C.F. Giulivi. 2014. Ocean eddy freshwater flux convergence into the North Atlantic subtropics. Journal of Geophysical Research 119:3,327–3,335, https://doi.org/10.1002/2013JC009596.

Gordon, A.L., C.F. Giulivi, J. Busecke, and F.M. Bingham. 2015. Differences among subtropical surface salinity patterns. Oceanography 28(1):32–39, https://doi.org/10.5670/oceanog.2015.02.

Held, I.M., and B.J. Soden. 2006. Robust responses of the hydrological cycle to global warming. Journal of Climate 19:5,686–5,699, https://doi.org/10.1175/JCLI3990.1.

Li, W., L. Li, M. Ting, and Y. Liu. 2012. Intensification of Northern Hemisphere subtropical highs in a warming climate. Nature Geoscience 5:830–834, https://doi.org/10.1038/ngeo1590.

Niiler, P., and J. Stevenson. 1982. The heat budget of tropical ocean warm-water pools. Journal Marine Research 40:465–480.

O’Connor, B.M., R.A. Fine, and D.B. Olson. 2005. A global comparison of subtropical underwater formation rates. Deep Sea Research Part I 52:1,569–1,590, https://doi.org/10.1016/j.dsr.2005.01.011.

Riser, S.C., J. Anderson, A. Shcherbina, and E. D’Asaro. 2015. Variability in near-surface salinity from hours to decades in the eastern North Atlantic: The SPURS region. Oceanography 28(1):66–77, https://doi.org/10.5670/oceanog.2015.11.

Rypina, I.I., I. Kamenkovich, P. Berloff, and L.J. Pratt. 2012. Eddy-induced particle dispersion in the near-surface North Atlantic. Journal of Physical Oceanography 42:2,206–2,228, https://doi.org/10.1175/JPO-D-11-0191.1.

Schanze, J.J., R.W. Schmitt, and L.L. Yu. 2010. The global oceanic freshwater cycle: A state-of-the-art quantification. Journal of Marine Research 68:569–595, https://doi.org/10.1357/002224010794657164.

Schmitt, R.W. 1995. The ocean component of the global water cycle. Reviews of Geophysics 33(S2):1,395–1,409, https://doi.org/10.1029/95RG00184.

Schmitt, R.W. 2008. Salinity and the global water cycle. Oceanography 21(1):12–19, https://doi.org/10.5670/oceanog.2008.63.

Schmitt, R.W., and D.L. Evans. 1978. An estimate of the vertical mixing due to salt fingers based on observations in the North Atlantic Central Water. Journal of Geophysical Research 83(C6):2,913–2,919, https://doi.org/10.1029/JC083iC06p02913.

Schmitt, R.W., J.R. Ledwell, E.T. Montgomery, K.L. Polzin, and J.M. Toole. 2005. Enhanced diapycnal mixing by salt fingers in the thermocline of the tropical Atlantic. Science 308:685–688, https://doi.org/10.1126/science.1108678.

Shcherbina, A.Y., E.A. D’Asaro, S.C. Riser, and W.S. Kessler. 2015. Variability and interleaving of upper-ocean water masses surrounding the North Atlantic salinity maximum. Oceanography 28(1):106–113, https://doi.org/10.5670/oceanog.2015.12.

SPURS-2 Planning Group. 2015. From salty to fresh—Salinity Processes in the Upper-ocean Regional Study-2 (SPURS-2): Diagnosing the physics of a rainfall-dominated salinity minimum. Oceanography 28(1):150–159, https://doi.org/10.5670/oceanog.2015.15.

St. Laurent, L., and R.W. Schmitt. 1999. The contribution of salt fingers to vertical mixing in the North Atlantic Tracer Release Experiment. Journal of Physical Oceanography 29:1,404–1,424, https://doi.org/10.1175/1520-0485(1999)029<1404:TCOSFT>2.0.CO;2.

Warren, B.A. 2009. Note on the vertical velocity and diffusive salt flux induced by evaporation and precipitation. Journal of Physical Oceanography 39:2,680–2,682, https://doi.org/10.1175/2009JPO4069.1.

Walin, G. 1982. On the relation between sea-surface heat flow and thermal circulation in the ocean. Tellus 34:187–195, https://doi.org/10.1111/j.2153-3490.1982.tb01806.x.

Wijffels, S.E., R.W. Schmitt, H.L. Bryden, and A. Stigebrandt. 1992. Transport of freshwater by the oceans. Journal of Physical Oceanography 22:155–162, https://doi.org/10.1175/1520-0485(1992)022<0155:TOFBTO>2.0.CO;2.

Worthington, L.V. 1976. On the North Atlantic Circulation. The Johns Hopkins Oceanographic Studies Number 6, Johns Hopkins University Press, Baltimore, MD, 110 pp.

Wright, D.G., R. Pawlowicz, T.J. McDougall, R. Feistel, and G.M. Marion. 2011. Absolute Salinity, “Density Salinity” and the Reference-Composition Salinity Scale: Present and future use in the seawater standard TEOS-10. Ocean Science 7(1):1–26, https://doi.org/10.5194/os-7-1-2011.

Wüst, G. 1936. Oberflachensalzgehalt, Verdunstung und Niederschlag auf den Weltmeere. Landerkundliche Forschung, Festschrift Norbert Krebs, 347–349.

Yang, J., S.C. Riser, J.A. Nystuen, W.E. Asher, and A.T. Jessup. 2015. Regional rainfall measurements using the Passive Aquatic Listener during the SPURS field campaign. Oceanography 28(1):124–133, https://doi.org/10.5670/oceanog.2015.10.

Copyright & Usage

This is an open access article made available under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution, and reproduction in any medium or format as long as users cite the materials appropriately, provide a link to the Creative Commons license, and indicate the changes that were made to the original content. Images, animations, videos, or other third-party material used in articles are included in the Creative Commons license unless indicated otherwise in a credit line to the material. If the material is not included in the article’s Creative Commons license, users will need to obtain permission directly from the license holder to reproduce the material.