Abstract: Based on -DDA data sets (GANAL/JMA) for TOGA-COARE IOP (from November 1992 to February 1993) which incorporated special upper-air observations, the large-scale flow pattern over the tropical Pacific for this period has been analysed. It has been found that frequent occurrence of stable and strong westerly wind or westerly wind bursting below 500 hPa and significant easterly wind at upper level over the central and western Pacific was observed; by the end of IOP, the westerlies shifted eastward to the eastern Pacific; the normal type East Asia-West Pacific Hadley cell and the Walker circulation were destroyed, with a significant inverse circulation sense observed. All the above anomalous circulation features lend supportive evidences for a developing El Niño event during TOGA -COARE IOP.