Intraseasonal Characteristics of the Indo-West Pacific Convection Oscillation

The principal modes of the intraseasonal variability over the Indo-West Pacific in different seasons are investigated using data filtered to retain the 30-60-day signal.A season-independent out-of-phase oscillation of convection over the Indo-West Pacific is the most clearly defined feature, with dipole centers over the equatorial eastern Indian Ocean (EEIO) (5°S-10°N, 70°E-100°E) and western North Pacific (WNP) (5°N-20°N, 110°E-160°E) regions.This is referred to as the intraseasonal Indo-West Pacific Convection Oscillation, or IPCO.Lead-lag correlation analysis of the convective activity between EEIO and WNP shows that the life cycle (formation-development-dissipation) of IPCO is driven by the behavior of the intraseasonal oscillation (ISO).The low-frequency convection anomaly first appears over the equatorial western central Indian Ocean.It intensifies and propagates eastward, splitting into two branches.One branch splits from the equatorial Indian Ocean northward to the south of the Indian Peninsula.The other splits eastward along the equator, which is suppressed over the maritime continent, re-amplified over the western Pacific, turns northward to the western North Pacific, and dissipates near the region lying between the middle and lower reaches of the Yangtze River and Japan.This process is divided into eight phases, and the circulation and precipitation characteristics of each phase are obtained; In conclusion, a schematic showing the IPCO event's life cycle is presented.