Precessional hydroclimatic synchronicity changes in the Indo-Pacific Warm Pool driven by the intertropical convergence zone over the past 450 kyr

The Indo-Pacific Warm Pool (IPWP) significantly influences the global hydrological cycle through its impact on atmospheric-oceanic circulation. However, gaining a comprehensive understanding of the hydrologic climate dynamics within the IPWP and its broader effects on the global climate have been hindered by spatial and temporal limitations in paleoclimate records on orbital timescales. In this study, we reconstructed precipitation records (approximated from delta O-18(sw-ivc)) over the past 450 kyr, based on planktonic foraminiferal Mg/Ca and delta O-18 data obtained from International Ocean Discovery Program Site U1486 in the western tropical Pacific. The delta O-18(sw-ivc) record revealed a generally consistent pattern with precession variations over the past 450 kyr, closely corresponding to changes in boreal summer insolation at the equator. The delta O-18(sw-ivc) record displayed an anti-phased relationship with Chinese speleothem delta O-18 records on the precession band, with lower precipitation in the western tropical Pacific and higher precipitation in the East Asia summer monsoon region during periods of high Northern Hemisphere summer insolation. This anti-phased correlation primarily resulted from the north-south migration of the Intertropical Convergence Zone (ITCZ), influenced by the interhemispheric insolation contrast. By considering additional delta O-18(sw-ivc) records from various locations within the IPWP region, we identified synchronous precipitation changes within the IPWP on the precession band. The synchronization of precipitation on both margins of the ITCZ's seasonal range and differences between central and marginal regions of the ITCZ within the IPWP revealed the expansion and contraction of the ITCZ on precession band.