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

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Volume 28, No. 1
Pages 114 - 123

Article Abstract

We investigated a 100 × 100 km high-salinity region of the North Atlantic subtropical gyre during the Sub-Tropical Atlantic Surface Salinity Experiment/Salinity Processes in the Upper-ocean Regional Study (STRASSE/SPURS) cruise from August 21, 2012, to September 9, 2012. Results showed great variability in sea surface salinity (SSS; over 0.3 psu) in the mesoscale, over 7 cm of total evaporation, and little diapycnal mixing below 36 m depth, the deepest mixed layers encountered. Strong currents in the southwestern part of the domain, and the penetration of freshwater, suggest that advection contributed greatly to salinity evolution. However, it was further observed that a smaller cyclonic structure tucked between the high SSS band and the strongest currents contributed to the transport of high SSS water along a narrow front. Cross-frontal transport by mixing is also a possible cause of summertime reduction of SSS. The observed structure was also responsible for significant southward salt transport over more than 200 km.

Citation

Reverdin, G., S. Morisset, L. Marié, D. Bourras, G. Sutherland, B. Ward, J. Salvador, J. Font, Y. Cuypers, L. Centurioni, V. Hormann, N. Koldziejczyk, J. Boutin, F. D’Ovidio, F. Nencioli, N. Martin, D. Diverres, G. Alory, and R. Lumpkin. 2015. Surface salinity in the North Atlantic subtropical gyre during the STRASSE/SPURS summer 2012 cruise. Oceanography 28(1):114–123, https://doi.org/10.5670/oceanog.2015.09.

References

Asher, W., A.T. Jessup, and D. Clark, 2014. Stable near-surface ocean salinity stratifications due to evaporation observed during STRASSE. Journal of Geophysical Research 119:3,219–3,233, https://doi.org/10.1002/2014JC009808.

Benetti, M., G. Reverdin, C. Pierre, L. Merlivat, C. Risi, H.C. Steen-Larsen, and F. Wimeux. 2014. Deuterium excess in marine water vapor: Dependency on relative humidity and surface wind speed during evaporation. Journal of Geophysical Research 119:584–593, https://doi.org/10.1002/2013JD020535.

Bourras, D., H. Branger, G. Reverdin, L. Marié, R. Cambra, L. Baggio, C. Caudoux, G. Caudal, S. Morisset, N. Geyskens, and others. 2014. A new platform for the determination of air-sea fluxes (OCARINA): Overview and first results. Journal of Atmospheric and Oceanic Technology 31:1,043–1,062, https://doi.org/10.1175/JTECH-D-13-00055.1.

Boutin, J., N. Martin, X. Yin, J. Font, N. Reul, and P. Spurgeon. 2012. First assessment of SMOS data over open ocean. Part II. Surface salinity. IEEE Transactions on Geoscience and Remote Sensing 50:1,662–1,675, https://doi.org/10.1109/TGRS.2012.2184546.

Boyer, T.P., and S. Levitus, Harmonic analysis of climatological sea surface salinity. Journal of Geophysical Research 107(C12), 8006, https://doi.org/10.1029/2001JC000829.

Capet, X., P. Klein, B.-L. Hua, G. Lapyere, and J.C. McWilliams. 2008. Surface kinetic energy transfer in surface quasi-geostrophic flows. Journal of Fluid Mechanics 604:165–174, https://doi.org/10.1017/S0022112008001110.

de Boyer Montégut, C., G. Madec, A.S. Fischer, A. Lazar, and D. Iudicone. 2004. Mixed layer depth over the global ocean: An examination of profile data and a profile-based climatology. Journal of Geophysical Research 109, C12003, https://doi.org/10.1029/2004JC002378.

d’Ovidio, F., J. Isern-Fontanet, C. Lopez, E. Hernandez-Garcia, and G.L. Emilio. 2009. Comparison between Eulerian diagnostics and finite-size Lyapunov Exponents computed from altimetry in the Algerian basin. Deep Sea Research Part I 56:15–31, https://doi.org/10.1016/j.dsr.2008.07.014.

Fairall, C.W., E.F. Bradley, D.P. Rogers, J.B. Edson, and G.S. Young. 1996. Bulk parameterization of air-sea fluxes for TOGA COARE. Journal of Geophysical Research 101:3,747–3,764.

Font, J., J. Boutin, N. Reul, P. Spurgeon, J. Ballabrera-Poy, A. Chuprin, C. Gabarro, J. Gourrion, S. Guimbard, C. Hénocq, and others. 2013. SMOS first data analysis for sea surface salinity determination. International Journal of Remote Sensing 34:3,654–3,670, https://doi.org/10.1080/01431161.2012.716541.

Gaillard, F. 2012. ISAS-Tool Version 6: Method and configuration. https://doi.org/10.13155/22583.

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.

Hernandez, O., J. Boutin, N. Kolodziejczyk, G. Reverdin, N. Martin, F. Gaillard, N. Reul, and J.L. Vergely. 2014. SMOS salinity in the subtropical North Atlantic salinity maximum: Part 1. Comparison with Aquarius and in situ salinity. Journal of Geophysical Research 11:8,878–8,896, https://doi.org/10.1002/2013JC009610.

Hosegood, P.J., M.C. Gregg, and M.H. Aleford. 2013. Wind-driven submesoscale subduction at the north Pacific subtropical front. Journal of Geophysical Research 118:5,332–5,352, https://doi.org/10.1002/jgrc.20385.

Kolodziejczyk, N., O. Hernandez, J. Boutin, and G. Reverdin. 2014a. SMOS salinity in the subtropical North Atlantic salinity maximum: Part 2. Two-dimensional horizontal thermohaline variability. Journal of Geophysical Research, https://doi.org/10.1002/2014JC010103.

Kolodziejczyk, N., G. Reverdin, and A. Lazar. 2014b. Interannual variability of the mixed layer winter convection and spice injection in the eastern subtropical North Atlantic. Journal of Physical Oceanography 45(2):504–525, https://doi.org/10.1175/JPO-D-14-0042.1.

Lagerloef, G., F. Wentz, S. Yueh, H.-Y. Kao, G.C. Johnson, and J.M. Lyman. 2012. Aquarius satellite mission provides new, detailed view of sea surface salinity. In State of the Climate 2011. Bulletin of the American Meteorological Society 93:S70–S71.

Mahadevan, A., and A. Tandon. 2006. An analysis of mechanisms for submesoscale vertical motion at ocean fronts. Ocean Modelling 14:241–256, https://doi.org/10.1016/j.ocemod.2006.05.006.

Reverdin, G., S. Morisset, D. Bourras, N. Martin, A. Lourenço, J. Boutin, C. Caudoux, J. Font, and J. Salvador. 2013. Surpact: A SMOS surface wave rider for air-sea interaction. Oceanography 26(1):48–57, https://doi.org/10.5670/oceanog.2013.04.

Rio, M.H. 2012. Use of altimeter and wind data to detect the anomalous loss of SVP-type drifter’s drogue. Journal of Atmospheric and Oceanic Technology 29:1,663–1,674, https://doi.org/10.1175/JTECH-D-12-00008.1.

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.

Sutherland, G., G. Reverdin, L. Marié, and B. Ward. 2014. Mixed and mixing layer depths in the ocean surface boundary layer: Buoyancy-driven conditions. Geophysical Research Letters 41:8,469–8,476, https://doi.org/10.1002/2014GL061939.

Thomas, L.N., and C.M. Lee. 2005. Intensification of ocean fronts by down-front winds. Journal of Physical Oceanography 35:1,086–1,102, https://doi.org/10.1175/JPO2737.1.

Ward, B., T. Fristedt, A.H. Callaghan, G. Sutherland, X. Sanchez, and J. Vialard. 2014. The Air-Sea Interaction Profiler (ASIP): An autonomous upwardly-rising profiler for microstructure measurements in the upper ocean. Journal of Atmospheric and Oceanic Technology 31:2,246–2,267, https://doi.org/10.1175/JTECH-D-14-00010.1.

Yueh, S.H., W. Tang, A.K. Hayashi, and G.S.E. Lagerloef. 2014. L-band passive and active microwave geophysical model functions of ocean surface winds and applications to Aquarius retrieval. IEEE Transactions on Geoscience and Remote Sensing 51:4,619–4,632, https://doi.org/10.1109/TGRS.2013.2266915.