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

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Volume 28, No. 1
Pages 56 - 65

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Salinity and Temperature Balances at the SPURS Central Mooring During Fall and Winter

By J. Thomas Farrar , Luc Rainville, Albert J. Plueddemann , William S. Kessler, Craig Lee , Benjamin A. Hodges, Raymond W. Schmitt, James B. Edson, Stephen C. Riser, Charles C. Eriksen , and David M. Fratantoni 
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Article Abstract

One part of the Salinity Processes in the Upper-ocean Regional Study (SPURS) field campaign focused on understanding the physical processes affecting the evolution of upper-ocean salinity in the region of climatological maximum sea surface salinity in the subtropical North Atlantic (SPURS-1). An upper-ocean salinity budget provides a useful framework for increasing this understanding. The SPURS-1 program included a central heavily instrumented mooring for making accurate measurements of air-sea surface fluxes, as well as other moorings, Argo floats, and gliders that together formed a dense observational array. Data from this array are used to estimate terms in the upper-ocean salinity and heat budgets during the SPURS-1 campaign, with a focus on the first several months (October 2012 to February 2013) when the surface mixed layer was becoming deeper, fresher, and cooler. Specifically, we examine the salinity and temperature balances for an upper-ocean mixed layer, defined as the layer where the density is within 0.4 kg m–3 of its surface value. The gross features of the evolution of upper-ocean salinity and temperature during this fall/winter season are explained by a combination of evaporation and precipitation at the sea surface, horizontal transport of heat and salt by mixed-layer currents, and vertical entrainment of fresher, cooler fluid into the layer as it deepened. While all of these processes were important in the observed seasonal (fall) freshening at this location in the salinity-maximum region, the variability of salinity on monthly-to-intraseasonal time scales resulted primarily from horizontal advection.

Citation

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.

References
    Beron-Vera, F.J., J. Ochoa, and P. Ripa. 1999. A note on boundary conditions for salt and freshwater balances. Ocean Modelling 1:111–118, https://doi.org/10.1016/S1463-5003(00)00003-2.
  1. Bourlès, B., R. Lumpkin, M.J. McPhaden, F. Hernandez, P. Nobre, E. Campos, L. Yu, S. Planton, A. Busalacchi, A.D. Moura, and others. 2008. The Pirata program: History, accomplishments, and future directions. Bulletin of the American Meteorological Society 89:1,111–1,125, https://doi.org/10.1175/2008BAMS2462.1.
  2. Colbo, K., and R.A. Weller. 2007. The variability and heat budget of the upper ocean under the Chile-Peru stratus. Journal of Marine Research 65:607–637, https://doi.org/10.1357/002224007783649510.
  3. Colbo, K., and R.A. Weller. 2009. Accuracy of the IMET sensor package in the subtropics. Journal of Atmospheric and Oceanic Technology 26:1,867–1,890, https://doi.org/10.1175/2009JTECHO667.1.
  4. Cronin, M.F., N.A. Bond, J.T. Farrar, H. Ichikawa, S.R. Jayne, Y. Kawai, M. Konda, B. Qiu, L. Rainville, and H. Tomita. 2013. Formation and erosion of the seasonal thermocline in the Kuroshio Extension recirculation gyre. Deep-Sea Research Part II 85:62–74, https://doi.org/10.1016/j.dsr2.2012.07.018.
  5. Durack, P.J. 2015. Ocean salinity and the global water cycle. Oceanography 28(1):20–31, https://doi.org/10.5670/oceanog.2015.03.
  6. 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.
  7. 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.
  8. Fairall, C.F., E.F. Bradley, J.E. Hare, A.A. Grachev, and J.B. Edson. 2003. Bulk parameterization of air-sea fluxes: Updates and verification for the COARE algorithm. Journal of Climate 16:571–591, https://doi.org/10.1175/1520-0442(2003)016<0571:BPOASF>2.0.CO;2.
  9. Farrar, J.T. 2007. Air-sea interaction at contrasting sites in the eastern tropical Pacific: Mesoscale variability and atmospheric convection at 10°N. PhD thesis, Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 166 pp.
  10. Foltz, G.R., S.A. Grodsky, J.A. Carton, and M.J. McPhaden. 2004. Seasonal salt budget of the northwestern tropical Atlantic Ocean along 38°W. Journal of Geophysical Research 109, C03052, https://doi.org/10.1029/2003JC002111.
  11. Gill, A.E. 1982. Atmosphere-Ocean Dynamics. Academic Press, San Diego, CA, 662 pp.
  12. Hodges, B.A., and D.M. Fratantoni. 2014. AUV observations of the diurnal surface layer in the North Atlantic Salinity Maximum. Journal of Physical Oceanography 44:1,595–1,604, https://doi.org/10.1175/JPO-D-13-0140.1.
  13. Holte, J., F. Straneo, J.T. Farrar, and R.A. Weller. 2014. Heat and salinity budgets at the Stratus mooring in the southeast Pacific. Journal of Geophysical Research 119:8,162–8,176, https://doi.org/10.1002/2014JC010256.
  14. Ledwell, J.R., A.J. Watson, and C.S. Law. 1993. Evidence for slow mixing across the pycnocline from an open-ocean tracer-release experiment. Nature 364:701–703, https://doi.org/10.1038/364701a0.
  15. Maximenko, N., P. Niiler, M.-H. Rio, O. Melnichenko, L. Centurioni, D. Chambers, V. Zlotnicki, and B. Galperin. 2009. Mean dynamic topography of the ocean derived from satellite and drifting buoy data using three different techniques. Journal of Atmospheric and Oceanic Technology 26:1,910–1,919, https://doi.org/10.1175/2009JTECHO672.1.
  16. McPhaden, M.J. 1982. Variability in the central equatorial Indian Ocean: Part II. Oceanic heat and turbulent energy balances. Journal of Marine Research 40:403–419.
  17. Niiler, P.P., and J.W. Stevenson. 1982. The heat budget of tropical ocean warm water pools. Journal of Marine Research 40:465–480.
  18. Pascual, A., Y. Faugère, G. Larnicol, and P.-Y. Le Traon. 2006. Improved description of the ocean mesoscale variability by combining four satellite altimeters. Geophysical Research Letters 33, L02611, https://doi.org/10.1029/2005GL024633.
  19. Qu, T., S. Gao, and I. Fukumori. 2013. Formation of salinity maximum water and its contribution to the overturning circulation in the North Atlantic as revealed by a global general circulation model. Journal of Geophysical Research 118:1,982–1,994, https://doi.org/10.1002/jgrc.20152.
  20. 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.
  21. Schmitt, R.W. 2008. Salinity and the global water cycle. Oceanography 21(1):12–19, https://doi.org/10.5670/oceanog.2008.63.
  22. Schmitt, R.W., and A.Blair. 2015. A river of salt. Oceanography 28(1):40–45, https://doi.org/10.5670/oceanog.2015.04.
  23. 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.
  24. St. Laurent, L. 2008. Turbulent dissipation on the margins of the South China Sea. Geophysical Research Letters 35, L23615, https://doi.org/10.1029/2008GL035520.
  25. Young, H.D. 1996. Statistical Treatment of Experimental Data: An Introduction to Statistical Methods. Waveland Press, Prospect Heights, IL.
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