Toga and atmospheric processes

A brief outline is given of the TOGA (Tropical Oceans and Global Atmosphere) Program along with a more detailed discussion of the relationship of the atmospheric circulation to sea surface temperatures (SSTs) in the tropics. The best known phenomenon that is part of TOGA is El Nino-Southern Oscillation (ENSO) and this paper focuses on the atmospheric component of ENSO. The similarities and differences among different ENSO events are reexamined as seen through a Southern Oscillation index and indices of SST in the tropical Pacific. Variations from event to event are marked and phase locking of ENSO events to the annual cycle is only weak. The 1986-87 ENSO has been especially anomalous with regard to timing. However, it provides an excellent illustration of the link between atmospheric convection and SSTs. The reasons why convection occurs where it does and the importance of warm water greater than 28°C are discussed. It is shown that there is a need to better understand the atmosphere-ocean links in the tropics and a need to measure more accurately and understand changes in SSTs.