A summary of the broadscale tropical circulation from 70°E to 180°, for the six months May to October 1998, is presented. El Niño conditions which were a feature of the global climate system in 1997 and early 1998 subsided and the opposite condition began to develop. Tropical convection was generally enhanced over the western half of the region, but suppressed over a large part of the Pacific portion. Tropical cyclone numbers, particularly in the northwest Pacific, were well below both the long-term average and numbers in the corresponding period of 1997. Intra-seasonal oscillations with an average period of 30 to 35 days were identifiable for much of the six-month season.
P.W. Bate (Mon,) studied this question.