The oceanic response to cross-equatorial winds (with application to coastal upwelling in low latitudes)

Sea surface temperature variations observed in the eastern equatorial Atlantic and Pacific Oceans on seasonal, and possibly interannual (El Nix±o) time scales, may to a large extent be due to the variability of the local meridional winds. In a numerical model of the ocean, southerly winds cause low sea surface temperatures in the southeastern part of the basin because the coastal upwelling zone is extended far westward by (1) advection and (2) Rossby wave propagation which is important on time scales greater than a month. North of the equator sea surface temperatures are high. The thermocline has a trough near 3°N where there is an intense eastward jet. A relaxation of the southerly wind causes a warming in the southeastern part of the basin primarily because of a zonal redistribution of heat by the South Equatorial Current and Countercurrent.