Seasonal changes in the tropics using 5-day mean data

The seasonal changes in the tropics are examined globally, using 5-day mean outgoing long wave radiation (OLR, 1976-87 except 1978) data obtained from NOAA series satellites and ECMWF operational objective analyses wind data (1980-88). Some distinct changes in the location and/or intensity of highly convective regions are recognized in transitional seasons. The onset of the summer monsoon season in Australia is not accompanied by distinct seasonal changes in other continents, and both the onset and retreat are drastic, while the period of the summer monsoon is the shortest among all continents. In South America, on the other hand, the period of the wet season is the longest, while the seasonal change is gradual. The onset of the Indian summer monsoon is the most drastic of all the continental summer monsoons. In Central America, the beginning and end of summer wet season are also drastic, and are almost simultaneous with those of summer wet season over the Bay of Bengal and Indochina