Oceanography The Official Magazine of
The Oceanography Society
Volume 32 Issue 02

View Issue TOC
Volume 32, No. 2
Pages 66 - 75

Observations of Near-Surface Salinity and Temperature Structure with Dual-Sensor Lagrangian Drifters During SPURS-2

Denis L. Volkov Shenfu DongGregory R. FoltzGustavo GoniRick Lumpkin
Article Abstract

Sea surface salinity (SSS) is among the key indicators of air-sea buoyancy fluxes and the global hydrological cycle. Contributing to the second phase of the Salinity Processes in the Upper-ocean Regional Study (SPURS-2) carried out in the precipitation-dominated Intertropical Convergence Zone of the eastern Pacific, we deployed six Lagrangian drifters equipped with two pairs of temperature and conductivity sensors at 0.4 m and 5 m depth. Over the first three months, the drifter measurements revealed that (1) the wind strongly affects surface freshening resulting from rainfall and diurnal warming so that near-surface salinity and temperature gradients generally do not form at wind speeds greater than 7 m s–1, (2) temperature and salinity differences between the two measurement depths are positively correlated for the cases of surface warming/salinification and freshening/cooling, (3) the lifetimes of rain-induced salinity anomalies can reach 24 hours, longer than previous estimates, (4) temperature (at 0.4 m and 5 m depth) and salinity (at 0.4 m depth) exhibit diurnal cycles, modulated by the wind, and (5) the differences that have been observed between satellite SSS and the standard uppermost salinity from Argo measurements are unlikely to be related to the difference in measurement depths (surface skin layer vs ~5 m depth).

Citation

Volkov, D.L., S. Dong, G.R. Foltz, G. Goni, and R. Lumpkin. 2019. Observations of near-​surface salinity and temperature structure with dual-​sensor Lagrangian drifters during SPURS-2. Oceanography 32(2):66–75, https://doi.org/10.5670/oceanog.2019.214.

References

Asher, W.E., A.T. Jessup, R. Branch, and D. Clark. 2014a. Observations of rain-induced near-​surface salinity anomalies. Journal of Geophysical Research 119:5,483–5,500, https://doi.org/​10.1002/​2014JC009954.

Asher, W.E., A.T. Jessup, and D. Clark. 2014b. 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.

Bellinger, H., K. Drushka, W. Asher, G. Reverdin, M. Katsumata, and M. Watanabe. 2017. Extension of the prognostic model of sea surface temperature to rain-induced cool and fresh lenses. Journal of Geophysical Research 122:484–507, https://doi.org/​10.1002/2016JC012429.

Boutin, J., N. Martin, G. Reverdin, X. Yin, and F. Gaillard. 2013. Sea surface freshening inferred from SMOS and Argo salinity: Impact of rain. Ocean Science 9:183–192, https://doi.org/10.5194/os-9-183-2013.

Boutin, J., Y. Chao, W.E. Asher, T. Delacroix, R. Drucker, K. Drushka, N. Kolodziejczyk, T. Lee, N. Reul, G. Reverdin, and others. 2016. Satellite and in situ salinity: Understanding near-surface stratification and subfootprint variability. Bulletin of the American Meteorological Society 97:1,391–1,407, https://doi.org/10.1175/BAMS-D-15-00032.1.

Cronin, M.F., and M.J. McPhaden. 1999. Diurnal cycle of rainfall and surface salinity in the Western Pacific Warm Pool. Geophysical Research Letters 26(23):3,465–3,468, https://doi.org/​10.1029/1999GL010504.

Dong, S., D. Volkov, G. Goni, R. Lumpkin, and G.R. Foltz. 2017. Near-surface salinity and temperature structure observed with dual-​sensor drifters in the subtropical South Pacific. Journal of Geophysical Research 122, https://doi.org/​10.1002/​2017JC012894.

Drushka, K., W.E. Asher, B. Ward, and K. Walesby. 2016. Understanding the formation and evolution of rain-formed fresh lenses at the ocean surface. Journal of Geophysical Research 121:2,673–2,689, https://doi.org/10.1002/2015JC011527.

EUMETSAT SAF on Ocean and Sea Ice. 2016. ASCAT L2 12.5 km winds data record release 1-Metop. OSI SAF, https://doi.org/10.15770/EUM_SAF_OSI_0007.

Fore, A.G., S.H. Yueh, W. Tang, B. Stiles, and A.K. Hayashi. 2016. Combined active/passive retrievals of ocean vector wind and sea surface salinity with SMAP. IEEE Transactions on Geoscience and Remote Sensing 54:7,396–7,404, https://doi.org/10.1109/TGRS.2016.2601486.

GMAO (Global Modeling and Assimilation Office). 2015. MERRA-2 inst1_2d_asm_Nx: 2d, 1-Hourly, Instantaneous, Single-Level, Assimilation, Single-Level Diagnostics V5.12.4. Greenbelt, MD, USA, Goddard Earth Sciences Data and Information Services Center (GES DISC), https://doi.org/​10.5067/​3Z173KIE2TPD.

Grodsky, S.A., J.A. Carton, and H. Liu. 2008. Comparison of bulk sea surface and mixed layer temperatures. Journal of Geophysical Research 113, C10026, https://doi.org/10.1029/2008JC004871.

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.

Huffman, G.J., R.F. Adler, D.T. Bolvin, and E.J. Nelkin. 2010. The TRMM Multi-satellite Precipitation Analysis (TMPA). Chapter 1 in Satellite Rainfall Applications for Surface Hydrology. https://doi.org/​10.1007/978-90-481-2915-7.

Kerr, Y.H., P. Waldteufel, J.-P. Wigneron, S. Delwart, F. Cabot, J. Boutin, M.-J. Escorihuela, J. Font, N. Reul, C. Gruhier, and others. 2010. The SMOS mission: New tool for monitoring key elements of the global water cycle. Proceedings of the IEEE 98:666–687, https://doi.org/10.1109/JPROC.2010.2043032.

Lagerloef, G., F.R. Colomb, D. Le Vine, F. Wentz, S. Yueh, C. Ruf, J. Lilly, J. Gunn, Y. Chao, A. deCharon, G. Feldman, and C. Swift. 2008. The Aquarius/SAC-D mission: Designed to meet the salinity remote-sensing challenge. Oceanography 21(1):68–81, https://doi.org/10.5670/oceanog.2008.68.

Lindstrom, E.J., A.Y. Shcherbina, L. Rainville, J.T. Farrar, L.R. Centurioni, S. Dong, E.A. D’Asaro, C. Eriksen, D.M. Fratantoni, B.A. Hodges, and others. 2017. Autonomous multi-platform observations during the Salinity Processes in the Upper-ocean Regional Study. Oceanography 30(2):38–48, https://doi.org/​10.5670/​oceanog.2017.218.

Reverdin, G., S. Morisset, J. Boutin, and N. Martin. 2012. Rain-induced variability of near sea-​surface T and S from drifter data. Journal of Geophysical Research 117, C02032, https://doi.org/​10.1029/​2011JC007549.

Rhein, M., S.R. Rintoul, S. Aoki, E. Campos, D. Chambers, R.A. Feely, S. Gulev, G.C. Johnson, S.A. Josey, A. Kostianoy, and others. 2013. Observations: Ocean. Pp. 255–315 in Climate Change 2013: The Physical Science Basis. Contributions of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. T.F. Stockeret D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex, and P.M. Midgley, eds, Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

Schanze, J.J., G. Lagerloef, R.W. Schmitt, and B.A. Hodges. 2014. Snakes on a ship: Surface salinity observations during SPURS. Extended Abstracts, 2014 Ocean Sciences Meeting, Honolulu, HI, ASLO-AGU, 073.

Supply, A., J. Boutin, J.-L. Vergely, N. Martin, A. Hasson, G. Reverdin, C. Mallet, and N. Viltard. 2017. Precipitation estimates from SMOS sea-​surface salinity. Quarterly Journal of the Royal Meteorological Society 144:103–119, https://doi.org/​10.1002/​qj.3110.

TRMM (Tropical Rainfall Measuring Mission). 2011. TRMM (TMPA) Rainfall Estimate L3 3 hour 0.25 degree x 0.25 degree V7. Greenbelt, MD, Goddard Earth Sciences Data and Information Services Center (GES DISC), https://doi.org/10.5067/TRMM/TMPA/3H/7.