Review on observational studies of western tropical Pacific Ocean circulation and climate

The Western Tropical Pacific (WTP) Ocean holds the largest area of warm water (>28 degrees C) in the world ocean referred to as the Western Pacific Warm Pool (WPWP), which modulates the regional and global climate through strong atmospheric convection and its variability. The WTP is unique in terms of its complex 3-D ocean circulation system and intensive multiscale variability, making it crucial in the water and energy cycle of the global ocean. Great advances have been made in understanding the complexity of the WTP ocean circulation and associated climate impact by the international scientific community since the 1960s through field experiments. In this study, we review the evolving insight to the 3-D structure and multi-scale variability of the ocean circulation in the WTP and their climatic impacts based on in-situ ocean observations in the past decades, with emphasis on the achievements since 2000. The challenges and open questions remaining are reviewed as well as future plan for international study of the WTP ocean circulation and climate.