GRL：Southward Shift and Intensification of the Intertropical Convergence Zone in the North Pacific Across the Mid-Pleistocene Transition

Xingxing Wang¹, Yue Wang¹, Kelsey A. Dyez², A. Christina Ravelo³, Chunxiao Sun¹, Fenghao Liu¹, Xiaoying Jiang¹, Zhimin Jian¹

¹State Key Laboratory of Marine Geology, Tongji University, Shanghai, China, 

²Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, USA,

³Department of Ocean Sciences, University of California, Santa Cruz, CA, USA

Abstract：The Hadley Circulation and associated westerlies strengthened and moved equatorward across the mid-Pleistocene transition (MPT). However, the evolution of the intertropical convergence zone (ITCZ) is still elusive due to the scarcity of long-term hydrological records from regions sensitive to the ITCZ change. Here, high-resolution sea surface salinity estimates derived from surface-dwelling planktic foraminiferal δ ¹⁸O and Mg/Ca in Ocean Drilling Program Site 871 reveal a long-term freshening trend in the central equatorial Pacific across the MPT. We attribute this secular reorganization of the precipitation-evaporation balance to the gradual southward migration and intensification of ITCZ in the North Pacific. It is inferred that the long-term evolution of the ITCZ was modulated by the increased meridional sea surface temperature gradients and the enhancements of trade winds across the MPT.

Full Article：https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2023GL105983