Bryan: Poleward Heat Transport by the Ocean 1137 References Bennett, A.F., Poleward heat fluxes in Southern Phys. Oceanogr., 11, 1171-1193, 1981. Roemmich, D., Estimation of meridional heat Hemisphere oceans, •. Phys. Oceano•r., õ, Fuglister, F.C., Atlantic OceanAtlas of Temp- flux in the North Atlantic by inverse methods, 785-798, 1978. erature and Salinity Profiles and Data from •. Phys. Ocean., 10, 1972-83, 1980. Bernstein, R.L., and W.B. White, Meridional the International Geophysical Year of 1957- Sarmiento, J.L., and K. Bryan, An ocean transport eddy heat flux in the Kuroshio Extension 58, Woods Hole Oceanographic Inst., Atlas model for the North Atlantic. J. Geophys. Current, •. Phys. Oceanogr., 12, 154-159, Series 1, 209 pp. 1960. Res., 87(Cl), 394-408, 1982. 1982. Geor•i, D.T., and J.M. Toole, The Antarctic Sciremammano, F. 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Oort, A.H., Glob81 Atmosphere Circulation Stat- Fu, L.L., The general circulation and meridional istics, 1958-1973, NOAAProf. Paper, 14, heat transport of the subtropical South U.S. •ov't. Printing Office, Washington,DC, (Received October •9, 1982; Atlantic determined by inverse methods, J. 323 pp, 1982. accepted January 6, 1983.) REVIEWSOF GEOPHYSICSAND SPACE PHYSICS, VOL. 21, NO. 5, PAGES1137-1148, JUNE1983 U.S. NATIONALREPORT TO INTERNATIONALUNION OF GEODESYAND GEOPHYSICS 1979-1982 EQUATORIAL OCEANOGRAPHY Mark A. Cane Dept. of Meteorologyand Physical Oceanography,MIT, Cambridge,MA 02139 E.S. Sarachik Center for Earth and Planetary Physics, Harvard Univ., Cambridge,MA 02138 Introduction stratification means that the ocean can respond strongly to basinwide winds on the climatically Interest and activity •in the equatorial important, and observationally accessible, oceans (defined arbitrarily as that part of the annual and interannual time scales. This reali- oceans within ten degrees of the equator) have zation has taken hold as the result of an inter- undergone a remarkable expansion in the last play among theory, modelling and observation. four years. The previous IUGG report (O'Brien, Linear wave ideas have provided a simple 1979) listed about one hundredreferences- the framework and commonlanguage to discuss a wide present one lists over two •hundred and fifty. range of equatorial phenomena. In particular, Among the many reasons for this growth, a pri- the equatorial Kelvin wave, which allows locally mary one is the realization of the rapid nature forced wind changes to be rapidly communicated of equatorial responses. The vanishing of the to the east of the forcing region, has been a Coriolis parameter in the presence of density particularly fruitful concept in equatorial oceanography. Linear and nonlinear numerical Copyright 1983 by the American Geophysical Union. models ranging from single layer shallow water models to full general circulation models have Paper number 3R0051. built upon these linear wave concepts to eluci- 0034-6853/83/003R-0051 $15.00 date the roles of stratification, mixing, and 1138 Cane and Sarachik: Equatorial Oceanography non-linearity in the dynamics of a wide variety ticns of thermoc!ine depth, mid-ocean currents, of phenomena in the equatorial oceans. In addi- and boundary currents. We will then review a tion, extensive observations taken during field problem which has just begun to receive serious programs in all three oceans have become avail- attention, namely the factors that determine SST able in the last four years: the GARP Atlantic variability in equatorial oceans. We then dis- Tropical Experiment (GATE) in the Atlantic (see cuss the status of our understanding of the most the GATE Atlas: Duing, Ostapoff and Merle, 1980 spectacular manifestation of SST variability, and the GATE Supplements to Deep-Sea Research; the E1 Nino- Southern Oscillation phenomenon. Duing, 1980, and Siedler and Woods, 1980), the We proceed to discuss the problem of observing Indian Ocean Experiment (INDEX, see the August the surface winds, which we regard as a funda- 1, 1980 issue of •.l•Jl•); and the intensive mental factor limiting our understanding of the year 1979-1980 of the First GARP Global Experi- equatorial oceans. Finally, we will try to ment (FGGE, see McCreary, Moore and Witte, identify those current trends that we expect to 1981). In addition, preliminary theoretical and bear fruit by the time of the next IUGG report, observational work is regularly and efficiently and some directions for the more distant future. transmitted by the Tropical Ocean-Atmosphere Newsletter (edited by D. Halpern, JISAO, Univer- Thermocline Variations sity of Washington, Seattle). Interest in equatorial oceanography has The thermocline in equatorial oceans tends also intensified outside the oceanographic com- to be quite shallow, with an average depth of munity. All available data shows that the trop- about 100 m. Because of the action of the eas- ical ocean dominates ocean heat transport both terly trade winds, the mean thermocline tends to in the mean and in annual variations (see Bryan, be deeper in the western parts of the ocean and 1982, for a recent review) and is therefore a shallower in the east.