Half-precessional cycle of thermocline temperature in the western equatorial Pacific and its bihemispheric dynamics
Zhimin Jian, Yue Wang, Haowen Dang, David W. Lea, Zhengyu Liu, Haiyan Jin, Yaqian Yin
Abstract
Significance The precessional insolation plays a critical role in modulating the low-latitude oceanographic changes through ENSO-like dynamics. While previous studies focused on the precessional insolation-induced low-latitude surface water changes, our well-dated, centennial-resolution proxy data and numerical simulation reveal the half-precession cycle of thermocline water temperature (TWT) in the western equatorial Pacific that directly linked to ENSO-like zonal temperature seesaw over the equatorial Pacific. These half-precessional TWT changes are proposed to originate from the interplay of subtropical-to-tropical thermocline anomalies forced by the antiphased meridional insolation gradients in the two hemispheres at the precessional band. This work illustrates that the tropical thermocline water could bridge the meridional climatic processes and the east−west ENSO-like dynamics at orbital timescales.