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- Title
Internal Wave Imprints on Temperature Fluctuations as Revealed by Rapid‐Sampling Deep Profiling Floats.
- Authors
Gao, Zhiyuan; Chen, Zhaohui; Huang, Xiaodong; Xu, Zhenhua; Yang, Haiyuan; Zhao, Zhongsheng; Ren, Chong; Wu, Lixin
- Abstract
Internal waves play important roles in modulating the temperature variations and heat transfers in stratified oceans. However, due to the deep ocean measuring approach limitations, it is still challengeable to characterize the temperature fluctuations induced by internal waves in the deep oceans below 2,000 m. In this study, a fleet of rapid‐sampling deep profiling floats with an approximately daily sampling rate was deployed in the northeastern South China Sea (SCS), Philippine Basin (PB), Mariana Arc (MA), and Kuroshio Extension (KE). Results show that the internal waves, internal tides or near‐inertial waves, have considerable imprints on local temperature fluctuations. Geographically, the internal wave induced temperature fluctuations are generally larger in the PB and MA, indicative of a strong deep signature of internal tides generated by local energetic tide‐topography interactions or radiation from remote sources. The temperature fluctuations at 4,000 m can reach up to 7 m°C in most regions, which may cover up real signals of temperature change, posing challenges to assess the deep ocean warming rate through currently insufficient deep profiling floats. Besides, the amplitude of isopycnal displacement in the PB and MA is evidently larger than in KE at 4,000 m, which implies enhanced diapycnal diffusivity and mixing in the deep layers of open oceans with rough topography. Plain Language Summary: Internal waves are ubiquitous in the global ocean, and their propagations are accompanied by the rise and falls of isopycnals which induce fluctuations in local temperature. However, in situ observations of high‐frequency temperature fluctuations in the deep ocean are still insufficient. Here we used a fleet of rapid‐sampling deep profiling floats to assess the temperature fluctuations induced by internal waves. We found that the magnitude of internal wave induced deep ocean temperature fluctuations is evidently stronger than the long‐term trend, especially in the Philippine Basin (PB) and Mariana Arc (MA) with rough topography. Therefore, a more cautious approach should be used to assess the deep ocean warming rate in areas with strong internal waves. Key Points: Internal waves are found to have considerable imprints on temperature fluctuations using rapid‐sampling deep profiling floatsThe temperature fluctuations can reach 7 m °C at 4,000 m, posing challenges to assess the real deep ocean warming rateThe internal waves induced temperature fluctuations in the deep ocean are generally larger in the Philippine Basin and Mariana Arc
- Subjects
SOUTH China Sea; INTERNAL waves; OCEAN waves; OCEANOGRAPHY; OCEAN temperature
- Publication
Journal of Geophysical Research. Oceans, 2021, Vol 126, Issue 12, p1
- ISSN
2169-9275
- Publication type
Article
- DOI
10.1029/2021JC017878