Recent cooling in the lower Pacific Ocean based on dynamically-consistent ocean syntheses

• Main Authors: Liao, Fanglou, Zhan, Peng, Wang, Xiao Hua, Liu, Zhiqiang, Hoteit, Ibrahim
• Other Authors: King Abdullah University of Science and Technology, Earth Science and Engineering Program, Physical Science and Engineering (PSE) Division, Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, The Sino-Australian Research Consortium for Coastal Management, School of Science, The University of New South Wales, Canberra, Australia
• Format: Report
• Language: unknown
• Published: Research Square Platform LLC 2022
• Subjects: McIntyre; Pacific; Southern Ocean
• Online Access: http://hdl.handle.net/10754/676726; https://doi.org/10.21203/rs.3.rs-1599666/v1

The thermal state from 1993–2017 in the lower Pacific Ocean (below 2 km) was investigated using two dynamically-consistent syntheses. We show a robust and bottom-intensified cooling. This Pacific cooling is mainly determined by the meridional heat exchange with the Southern Ocean and the vertical heat advection. The abyssal Pacific Ocean loses heat by way of westward heat advection in the northwest ocean. Mixing is found to play a negligible role. This study is to some extent consistent with a recent study that presented a deep Pacific cooling as an adjustment to the last Little Ice Age. However, it contradicts with most recent studies, which argued the abyssal Pacific Ocean was warming over the recent two decades. Our study suggests that special caution is needed when auditing variations in the deep ocean and more work is in need for a better understanding of the deep ocean state. We thank the ECCO and GECCO teams for the publicly available datasets. Dr. Peter McIntyre helped to improve the manuscript. An earlier version of this manuscript was commented by Dr. Jiping Xie. We are also grateful for Hong Zhang from the Jet Propulsion Laboratory in helping with the heat budget analysis and Yang Zhang from University of Delaware for providing information about potential bias of using sparse observations in auditing the abyssal warming/cooling in the Pacific Ocean.