A synoptic overview of the tropical circulation between 70°E and the dateline is presented for the period May to October 1987, encompassing the northern summer monsoon and the southern hemisphere winter. Analyses of upper and lower tropospheric flow, sea surface temperature, cyclone tracks, circulation indices and rainfall data over South-East Asia, India and Australia are discussed. A moderate El Niño warm event in its declining phase appeared to exert a broad influence over the area during the period. The ascending arm of the Walker cell was displaced eastward to the dateline. Summer monsoon onset over India and Asia was late and weaker than normal. Monsoon rainfall was well below normal. Winter rainfall over Indonesia, Papua New Guinea and parts of the southwest Pacific was suppressed. On the other hand, cyclone activity in the northwest Pacific was average, although the area of genesis was displaced eastward. Low-frequency oscillations in the 30 to 50-day mode were found to be distinct in the pressures and upper winds of South-East Asia and the west Pacific.
Garden et al. (Thu,) studied this question.