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

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Volume 32, No. 2
Pages 20 - 29

Patterns of SSS Variability in the Eastern Tropical Pacific: Intraseasonal to Interannual Timescales from Seven Years of NASA Satellite Data

Oleg Melnichenko Peter HackerFrederick M. BinghamTong Lee
Article Abstract

Sea surface salinity (SSS) observations from NASA’s satellite missions, Aquarius/SAC-D and Soil Moisture Active Passive (SMAP), are used to describe spatial patterns of the seasonal cycle, as well as intraseasonal and interannual variability, in the eastern tropical Pacific, the location of the second Salinity Processes in the Upper-ocean Regional Study (SPURS-2) field experiment. The results indicate that the distribution of SSS variance is highly inhomogeneous in both space and time. The seasonal signal is largest in the core of the Eastern Pacific Fresh Pool and in the Gulf of Panama. The interannual signal is highest in a relatively narrow zonal band along approximately 5°N, while the intraseasonal signal appears to be a dominant mode of variability in the zonally stretched near-equatorial region. Located right in the middle of a hotspot of high SSS variance, the SPURS-2 site appears to be at the crossroads of many different processes that shape the distribution of SSS in the eastern tropical Pacific and beyond.


Melnichenko, O., P. Hacker, F.M. Bingham, and T. Lee. 2019. Patterns of SSS variability in the eastern tropical Pacific: Intraseasonal to interannual timescales from seven years of NASA satellite data. Oceanography 32(2):20–29, https://doi.org/10.5670/oceanog.2019.208.


Alory, G., C. Maes, T. Delcroix, N. Reul, and S. Illig. 2012. Seasonal dynamics of sea surface salinity off Panama: The far Eastern Pacific Fresh Pool. Journal of Geophysical Research 117, C04028, https://doi.org/​10.1029/2011JC007802.

Bingham, F.M., G.R. Foltz, and M.J. McPhaden. 2010. Seasonal cycles of surface layer salinity in the Pacific Ocean. Ocean Science 6:775–787, https://doi.org/10.5194/os-6-775-2010.

Bingham, F.M., V. Tsontos, A. deSharon, C.J. Lauter, and L. Taylor. 2019. The SPURS-2 eastern tropical Pacific field campaign data collection. Oceanography 32(2):142–149, https://doi.org/​10.5670/oceanog.2019.222.

Chelton, D.B., M.G. Schlax, and R.M. Samelson. 2011. Global observations of nonlinear mesoscale eddies. Progress in Oceanography 91:167–216, https://doi.org/10.1016/j.pocean.2011.01.002.

Delcroix, T., and C. Henin. 1991. Seasonal and interannual variations of sea surface salinity in the tropical Pacific Ocean. Journal of Geophysical Research 96:22,135–22,150, https://doi.org/​10.1029/91JC02124.

Delcroix, T. 1998. Observed surface oceanic and atmospheric variability in the tropical Pacific at seasonal and ENSO timescales: A tentative overview. Journal of Geophysical Research 103:18,611–18,633, https://doi.org/​10.1029/98JC00814.

Delcroix, T., A. Chaigneau, D. Soviadan, J. Boutin, and C. Pegliasco. 2019. Eddy-induced salinity changes in the tropical Pacific. Journal of Geophysical Research 124:374–389, https://doi.org/​10.1029/​2018JC014394.

Farrar, J.T., and R.A. Weller. 2006. Intraseasonal variability near 10°N in the eastern tropical Pacific Ocean. Journal of Geophysical Research 111, C05015, https://doi.org/10.1029/2005JC002989.

Fiedler, P.C., and L.D. Talley. 2006. Hydrography in the eastern tropical Pacific: A review. Progress in Oceanography 69:143–180, https://doi.org/10.1016/​j.pocean.2006.03.008.

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.

Guimbard, S., N. Reul, B. Chapron, M. Umbert, and C. Maes. 2017. Seasonal and interannual variability of the Eastern Tropical Pacific Fresh Pool. Journal of Geophysical Research 122:1,749–1,771, https://doi.org/10.1002/2016JC012130.

Hasson, A., M. Puy, J. Boutin, E. Guilyardi, and R. Morrow. 2018. Northward pathway across the tropical North Pacific Ocean revealed by surface salinity: How do El Niño anomalies reach Hawaii? Journal of Geophysical Research 123:2,697–2,715, https://doi.org/10.1002/2017JC013423.

Huffman, G.J., D.T. Bolvin, and R.F. Adler. 2016. GPCP version 1.2 One-Degree Daily Precipitation Data Set. Research Data Archive at the National Center for Atmospheric Research, Computational and Information Systems Laboratory, https://doi.org/​10.5065/D6D50K46.

Kessler, W.S. 2006. The circulation in the eastern tropical Pacific: A review. Progress in Oceanography 69:181–217, https://doi.org/10.1016/​j.pocean.2006.03.009.

Lee, T., G. Lagerloef, M. Gierach, H.-Y. Kao, S. Yueh, and K. Dohan. 2012. Aquarius reveals salinity structure of tropical instability waves. Geophysical Research Letters 39, L12610, https://doi.org/​10.1029/​2012GL052232.

Lindstrom, E., F. Bryan, and R. Schmitt. 2015. SPURS: Salinity Processes in the Upper-ocean Regional Study—The North Atlantic Experiment. Oceanography 28(1):14–19, https://doi.org/10.5670/oceanog.2015.01.

Maes, C., N. Reul, D. Behringer, and T. O’Kane. 2014. The salinity signature of the equatorial Pacific cold tongue as revealed by the satellite SMOS mission. Geoscience Letters 1:17, https://doi.org/10.1186/s40562-014-0017-5.

McPhaden, M.J., S.E. Zebiak, and M.H. Glantz. 2006. ENSO as an integrating concept in Earth science. Science 314:1,740–1,745, https://doi.org/10.1126/science.1132588.

Melnichenko, O., P. Hacker, N. Maximenko, G. Lagerloef, and J. Potemra. 2016. Optimum interpolation analysis of Aquarius sea surface salinity. Journal of Geophysical Research 121:602–616, https://doi.org/10.1002/2015JC011343.

Melnichenko, O., P. Hacker, T. Meissner, F. Wentz, and J. Potemra. 2018. Building a consistent multi-satellite SSS data record: A case study in the eastern tropical Pacific (SPURS-2). Paper presented at the 2018 Ocean Salinity Science Team and Salinity Continuity Processing Meeting, August 27–29, 2018, Santa Rosa, CA, https://salinity.oceansciences.org/docs/ossc2018_melnichenko_b.pdf.

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.

Tchilibou, M., T. Delcroix, G. Alory, S. Arnault, and G. Reverdin. 2015. Variations of the tropical Atlantic and Pacific SSS minimum zones and their relations to the ITCZ and SPCZ rain bands (1979–2009). Journal of Geophysical Research 120:5,090–5,100, https://doi.org/10.1002/2015JC010836.

US CLIVAR Office. 2007. Report of the US CLIVAR Salinity Working Group. US CLIVAR Report 2007-1, Washington, DC, 46 pp., https://usclivar.org/sites/default/files/Salinity_final_report.pdf.

Yu, L., and R.A. Weller. 2007. Objectively analyzed air-sea heat fluxes for the global ice-free oceans (1981–2005). Bulletin of the American Meteorological Society 88:527–529, https://doi.org/​10.1175/BAMS-88-4-527.

Yu, L. 2014. Coherent evidence from Aquarius and Argo for the existence of a shallow low-​salinity convergent zone beneath the Pacific ITCZ. Journal of Geophysical Research 119:7,625–7,644, https://doi.org/​10.1002/2014JC010030.

Xie, S.-P., and P. Arkin. 1996. Analysis of global monthly precipitation using gauge observations, satellite estimates, and numerical model predictions. Journal of Climate 9:840–858, https://doi.org/10.1175/1520-0442(1996)009​<0840:AOGMPU>2.0.CO;2.