The meridional advective heat flux was generally small, perhaps because the site is directly on the equator. This term can, however, contribute to the intraseasonal fluctuations. For example, meridional advection supplied nearly 100 W m in January 1987 during the passage of the Kelvin wave event. As noted above, this contribution from the meridional velocity is, presumably, indicative of the effects which the Kelvin signal has on the instability waves. However, if the diffusive heat flux is proportional to the meridional curvature of the temperature field, then the phase of this term is reasonably well represented in our analysis.
Meridional diffusion appears to be important in the seasonal heating.
In 1986 and 1988 this meridional term was crucial in order to obtain a near balance in the January heat budget. In February-March of each year the equatorial cold tongue nearly vanished at 110 W and the temperature curvature was a minimum. At this time the instability waves disappeared and the diffusive heat flux was near zero. In April-May the equatorial cold tongue returned and meridional diffusion tended to warm the equator. This warming is counter to the general cooling trend in the mixed layer and slows the development of the cold tongue.