THE western equatorial Pacific has an important role in the El Niño/Southern Oscillation climate cycle1,2, and sea-surface temperature anomalies in this area are known to affect the global atmospheric circulation3. Little is known, however, about the factors that control the response of the upper ocean, and hence sea surface temperature, to changes in atmospheric conditions. Here we present observations of the density and current structure of the upper layers of the western equatorial Pacific Ocean. We observed frontal features with temperature differences of 1 °C extending from the surface down to a depth of 150 m, a strong salinity front associated with a surface convergence, and interleaving of high-and low-salinity waters in 10-m-thick layers that extended for several hundred kilometres in the north-south direction. The large spatial and temporal variability in temperature and salinity observed must influence heat transport, and hence the ocean response to atmospheric forcing (in particular the response to westerly wind bursts, which are thought to be precursors to an El Niño). We estimate the horizontal diffusion coefficient of the interleaving, which indicates that the observed layering may con-tribute to horizontal mixing within the thermocline.
Subscribe to Journal
Get full journal access for 1 year
only $3.90 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
Gill, A. E. & Rasmussen, E. M. Nature 306, 229–234 (1983).
Lukas, R. & Lindstrom, E. Proc. ‘Aha Huliko’ a Hawaiian Winter Workshop on the Dynamics of the Ocean Surface Mixed Layer (eds Muller, P. & Henderson, D.) 67–94 (Hawaii Institute of Geophysics, University of Hawaii, Honolulu, 1987).
Palmer, T. N. & Mansfield, D. A. Nature 330, 533–537 (1984).
Colin, C., Henin, C., Hisard, P. & Oudot, C. Cah ORSTROM Ser. Oceanogr. 7, 167–186 (1971).
Garwood, R. W. Jr, Muller, P. & Gallacher, P. C. J. phys. Oceanogr. 15, 1332–1338 (1985).
Lindstrom, E. et al. Nature 330, 533–537 (1987).
McPhaden, M. J., Freitag, H. P., Hayes, S. P. & Taft, B. A. J. geophys. Res. 93, 10589–10603 (1988).
Peters, H. & Gregg, M. C. Proc. ‘Aha Huliko’ a Hawaiian Winter Workshop on the Dynamics of the Ocean Surface Mixed Layer (eds Muller, P. & Henderson, D.) 25–45 (Hawaii Institute of Geophysics, University of Hawaii, Honolulu, 1987).
Bahr, F., Firing, E. & Songnian, J. Joint Institute for Marine and Atmospheric Research, Data Rep. no. 5 (University of Hawaii, Honolulu, 1989).
Gregg, M. J. phys. Oceanogr. 10, 1468–1492 (1980).
McDougall, T. J. phys. Oceanogr. 15, 1532–1541 (1985).
Toole, T. J. & Georgi, D. T. Progr. Oceanogr. 10, 123–145 (1981).
Richards, K. J. J. phys. Oceanogr. (in the press).
Ruddick, B. & Hebert, D. in Small-Scale Turbulence and Mixing in the Ocean (eds Nihou, J. & Jamart, B.) 249–262 (Elsevier, Amsterdam, 1988).
About this article
Cite this article
Richards, K., Pollard, R. Structure of the upper ocean in the western equatorial Pacific. Nature 350, 48–50 (1991) doi:10.1038/350048a0
Geophysical Research Letters (2018)
Geophysical Research Letters (2014)
Acta Oceanologica Sinica (2013)
Geochimica et Cosmochimica Acta (2006)
Journal of Physical Oceanography (2005)