Vol. 17, No.7 Reviews of Geophysics and Space Physics

Introduct ion papers wi~ appear in ~ Sea Research in 1979. Duing (1974) and Philander Ti"974) describe the experimental rationale and design f:or the GATE oceanographic program. Duing, et al. (1975) found large scale meandering of the westward flowing south equatorial current and the east'Ward flowing equatorial undercurrent. They deduced the presence of: a long wave of wavelength 2600 km propagating westward at 1.9 m s-l. Horigan, et al. (1975) report on two months of: current meter measurements in eastern equatorial Atlantic and evidence f:or enhanced kinetic energy near the 5-day periods. Weisberg, et al. (1979) have pUblished a u.>re complete report. Katz, et al. (1977) report that the zonal pressure gradient between 10OW and 35OW has a pronounced annual signal. This is an important part .of: the justification f:or the reu.>te f:orcing ideas to explain the Gulf: of: Guinea upwe~ing. It is dif:f:icult to be can.plete here until the entire GATE oceanography report is published. However, two Ph.D. theses are available. Crawf'ord (1976) measured turbulent energy dissipation in the equatorial undercurrent and Hallock (1977) built a model of: wind-forced waves at the equator to explain the meandering of: the undercurrent with a l6-day period. The equatorial ocean has alwa;ys captured the attention of oceanographers. Almost all mediumto-J.arge scale oceanic ~tions are dominated by the effect of the earth's rotation, the Coriolis acceleration. At the equator, this apparent acceleration vanishes and very special PhYsics apply. The ~st striking phenomena is upwelling that occurs in a narrow latitude band a few degrees vide along the equator due to the prevailing easterlies (westward vinds). Whalers have known for over a century that this upwelling and its high biological productivity create an excellent line along which to search for whales. The meteorology ca8unity has identified the data sparse equatorial regions for special consideration in possibilities to improve long range weather forecasting. Since geostrophY" breaks down, the traditional pressure-height data is unable to estimate the motion field. In the summer of 1974, a massive experiment, the GARP Atlantic Tropical Experiment (GATE) was held to study the tropical atmosphere. On most of the GATE ships, various oceanographic experiments were perforlRed. Most of the U.S. contributions are to be published in ~ ~ Research in 1979 and vill not be reported here. It is now believed that the key to understanding interannual climate variations is linked to large scale air-sea interactions and spatial teleconnections between the ocean and the atmosphere in the equatorial regions. Several pilot experiments have been performed in the Borth Pacific Experiment (NORPAX) during the Quadrennial but have yet to be described in the literature. Several groups are planning experiments in the equatorial Pacific and Atlantic in the next few years and work is unde!"V~ at this time in the Arabian Sea under the Monsoon Experiment (MONEX). This report reviews the papers published during 1975-1978. A more exciting report will have to be vri tten in four years. We will refer to a few other key papers that put the latest work in a long range perspective. A few important papers which are accepted in 1979 are cited. Hopefully, this report will be a background primer for e:x:peri~nts being conts.plated. This review is organized by ocean with a small section on general theoretical papers. Where possible, the theory is discussed in the appropriate ocean section.