1. 1. Barnett, T. P. J. phys. Oceanogr. 7, 633–647 (1977). 2. Nicholls, N. Nature 307, 576–577 (1983). 3. Meyers, G., Donguy, J. R. & Reed, R. K. Nature 323, 523–526 (1986). 4. Rasmusson, E. M. & Carpenter, T. H. Man. Weath. Rev. 110, 354–384 (1982). 5. Philander, S. G. H. Nature 302, 295–301 (1983). 6. Tsuchiya, M. Johns Hopkins Oceanogr. Stud. No. 4 (1968). 7. Harries, J. R. & Calf, G. E. J. mar. Res. 40, 903–913 (1982). 8. Church, J. A. & Boland, F. M. / phys. Oceanogr. 13, 1746–1749 (1983). 9. Church, J. A. Aus. J. mar. freshw. Res. (in the press). 10. Wyrtki, K. Science 181, 262–264 (1973). 11. Knox, R. A. Deep Sea Res. 23, 211–221 (1976). 12. Cane, M. Deep Sea Res. 27, 525–544 (1980). 13. Hansen, D. V. & Paul, C. A. J. geophys. Res. 89, 10431–10440 (1984). 14. Schott, G., Ann. Hydrogr. Mar. Met., 67, 247–257 (1939). 15. Ministry of the Defence of the USSR World Ocean Atlas: Pacific Ocean (Pergamon, Oxford, 1974). 16. Moore, D. W. & Philander, S. G. H. The Sea: Ideas and Observations on Progress in the Study of the Seas (ed. Goldberg, E. D.) 319–361 (1977). 17. Garwood, R. W. Jr, Muller, P. & Gallacher, P. C. J. phys. Oceanogr. 15, 1332–1338 (1985). 18. Lemasson, L. & Piton, B. Cah. ORSTOM, Ser. Oceanogr. 6, 39–45 (1968). 19. Halpern, D. Deep Sea Res. 27, 931–940 (1980). 20. Lukas, R. & Lindstrom, E. J. Proc. "Aha Huliko' a Hawaiian Winter Workshop on the Mixed Layer (Hawaii Institute of Geophysics, University of Hawaii, in the press).