THE TROPICAL OCEAN GLOBAL ATMOSPHERE PROGRAM

TOGA was a ten year programme to advance understanding between the atm osphere and ocean which influence climate over interannual time-scales . During its lifetime, a major observational system for the tropical P acific Ocean was established, with measurements of surface air tempera ture, surface wind, sea surface temperature, upper ocean thermal struc ture, ocean currents and sea level being taken on a regular basis, and with trial deployments of instruments to measure surface pressure, ra infall and salinity under way. Armed with these data, oceanographers a nd meteorologists not only can analyse the present state of the ocean and atmosphere but even can predict climate change for several months ahead. Before TOGA, ideas of tropical atmosphere-ocean interaction wer e hazy. Ten years on, still no complete theory exists, but considerabl e progress has been made in modelling and in understanding some aspect s of that interaction. In particular the largest climate signal on int erannual time-scales, El Nine Southern Oscillation (ENSO), with its or igins in the tropical Pacific is much better understood. TOGA also est ablished a minimum observing system in the Atlantic and Indian Oceans. There are both interannual and decadal signals in these oceans which are related to climate variability, but the full role of these oceans in climate variability has yet to be clarified The primary heat source for the atmosphere is located over the 'warmpool' of the western trop ical Pacific. A major experiment, the coupled ocean atmosphere respons e experiment (COARE) was mounted to understand in some detail oceanic and atmospheric processes occurring in this region. It is not known ho w the tropical interaction processes such as ENSO will alter as a resu lt of anthropogenic increase in the radiatively active gases carbon di oxide, methane and sulphur dioxide, but there is a hint that some of t he global warming of the last decade may have an ENSO connection.