Influence of the Kuroshio Intrusion on Deep Flow Intraseasonal Variability in the Northern South China Sea
Abstract
Interactions between the open ocean and marginal seas have been suggested to be critical to the redistribution and dissipation of global energy. Here, we propose a mechanism for the upper open ocean influencing the deep flow in marginal seas that hinges on the formation and propagation of topographic Rossby waves (TRWs). Observations and high-resolution simulations suggest substantial intraseasonal variability with periods of 5–60 days associated with the deep flow over continental slopes of the northern South China Sea (NSCS). These fluctuations generally account for over 40% of the total deep kinetic energy variability and the number can reach 70% over the slopes to the west of the Luzon Strait, southwest of the Dongsha Islands, and northeast of the Xisha Islands. By examining the spatiotemporal features of the fluctuations, we demonstrate that the intraseasonal variability of the deep flow in the NSCS is closely associated with TRWs. Using a recently developed multiscale energetics analysis in combination with a ray tracing model, we show that the energy sources of TRWs can be traced back to the east of the Dongsha Islands, where the Kuroshio intrusion and related eddies energize the TRWs primarily through pressure work. These waves propagate westward across the NSCS and drive the intraseasonal variability of the deep flow over continental slopes. Our findings highlight an energy pathway from the open ocean western boundary current to the abyssal marginal sea that could modulate regional circulation as well as exchanges between major ocean basins.
Additional Information
© 2021 American Geophysical Union. Issue Online: 30 June 2021; Version of Record online: 30 June 2021; Accepted manuscript online: 22 June 2021; Manuscript accepted: 20 June 2021; Manuscript revised: 25 May 2021; Manuscript received: 31 March 2021. This study is supported by the National Natural Science Foundation of China (42006007; 41906016; 42006009; 41806023; 41975064), the China Postdoctoral Science Foundation (2020M682767; 2020M681269), the Science and Technology Development Fund, Macau SAR (SKL-IOTSC-2021-2023), the Natural Science Foundation of Guangdong Province (2019A1515011487), and the Fundamental Research Funds for the Central Universities (20184200031610059). The authors appreciate three anonymous reviewers for their insightful comments and Dr. Yukun Qian for discussions that improve this manuscript. Data Availability Statement: The mooring data are available at https://doi.org/10.6084/m9.figshare.13525838. The HYCOM data can be accessed from https://www.hycom.org/dataserver/gofs-3pt1/analysis. The satellite altimeter data were downloaded from https://resources.marine.copernicus.eu/?option=com_csw&task=results.Attached Files
Published - 2021JC017429.pdf
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Additional details
- Eprint ID
- 109944
- Resolver ID
- CaltechAUTHORS:20210720-223659345
- 42006007
- National Natural Science Foundation of China
- 41906016
- National Natural Science Foundation of China
- 42006009
- National Natural Science Foundation of China
- 41806023
- National Natural Science Foundation of China
- 41975064
- National Natural Science Foundation of China
- 2020M682767
- China Postdoctoral Science Foundation
- 2020M681269
- China Postdoctoral Science Foundation
- SKL-IOTSC-2021-2023
- Science and Technology Development Fund
- 2019A1515011487
- Natural Science Foundation of Guangdong Province
- 20184200031610059
- Fundamental Research Funds for the Central Universities
- Created
-
2021-07-21Created from EPrint's datestamp field
- Updated
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2022-02-02Created from EPrint's last_modified field