Article
Oceanography
Xiaohui Xie, Yan Wang, Zhiyu Liu, Xiaohui Liu, Dake Chen, Dongsheng Zheng, Jiannan Wang
Summary: The study investigates the energy dissipation mechanism of low-frequency flows in the abyssal ocean, specifically focusing on the role of the bottom boundary layer (BBL). In situ data collected near an abyssal seamount in the western Pacific Ocean shows that strong bottom-trapped flows over sloping topography can lose their energy to near-inertial waves (NIWs) generated by the adjustment of the bottom Ekman layer. These waves have near-resonant frequencies corresponding to internal waves and are strongest in the BBL. The generation of internal waves via Ekman transport adjustment plays an important role in damping the subinertial flows over the sloping seafloor.
JOURNAL OF PHYSICAL OCEANOGRAPHY
(2023)
Article
Oceanography
Wei Yang, Hao Wei, Zhiyu Liu, Liang Zhao
Summary: Based on microstructure measurements in the summer of 2013 and 2017, this study reports the widespread occurrence of intensified pycnocline turbulence in the stratified Yellow Sea. The elevated turbulent kinetic energy dissipation and microscale thermal dissipation are found in the pycnocline, which have important implications for nutrient cycling and primary productivity in the summer stratified Yellow Sea.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2023)
Article
Oceanography
Hongyang Lin, Siyu Xu, Zhiyu Liu, Jianyu Hu, Fangtao Zhang, Zhiyong Cao
Summary: This study uses high-resolution, cross-frontal towed measurements to investigate temperature-salinity (T-S) compensation and its scale dependence in the Taiwan Strait. It is found that T-S compensation occurs within the interfacing zone, with temperature and salinity getting more (less) compensated at smaller scales in the S-dominated (T-dominated) frontal zone. The restratification-cooling mechanism, induced by submesoscale instabilities, explains the observed density compensating features on both flanks of the transition zone.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2023)
Article
Environmental Sciences
Duhan Shen, Jianing Wang, Zhiyu Liu, Fan Wang
Summary: Diapycnal mixing in the upper western equatorial Pacific (WEP) is important for tropical air-sea interactions and the global climate system. The WEP is unique in water masses from both hemispheres and multi-scale processes, creating a complex mixing regime that needs to be fully characterized by observations.
FRONTIERS IN MARINE SCIENCE
(2023)
Article
Geosciences, Multidisciplinary
Xiaolin Bai, Kevin G. Lamb, Zhiyu Liu, Jianyu Hu
Summary: Predicting the occurrence of internal solitary-like waves (ISWs) is crucial for understanding turbulent dissipation. In the northern South China Sea, ISWs mainly originate from the Luzon Strait and their occurrence is predictable due to their phase-locked relation with tidal forcing. However, our measurements on the SCS shelf show irregular occurrence of ISWs, with more energetic waves appearing during the neap tide instead of the spring tide. This unexpected behavior is related to subtidal shelf flows, and can be explained by the hypothesis that locally generated ISWs occur when the total flow meets critical conditions over irregular seafloor.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Oceanography
Zhendong Hu, Hongyang Lin, Zhiyu Liu, Zhiyong Cao, Fangtao Zhang, Zongpei Jiang, Yao Zhang, Kuanbo Zhou, Minhan Dai
Summary: In this study, an elaborate observation of a warm and fresh filament intruding into a cyclonic mesoscale eddy is reported. The filament originated from an anticyclonic eddy and its evolution was mainly due to the geostrophic flows associated with the eddy pair. The findings provide important insights into the dynamics and transport properties of oceanic submesoscale flows.
JOURNAL OF PHYSICAL OCEANOGRAPHY
(2023)
Article
Oceanography
Chuanyin Wang, Zhiyu Liu, Hongyang Lin
Summary: A long-standing challenge in dynamical oceanography is distinguishing nonlinearly intermingled dynamical regimes of oceanic flows. Conventional approaches focus on time-scale or space-scale decomposition. In this study, a dynamics-based decomposition is pursued, where a mean flow is introduced to extend the classic theory of wavy and vortical modes. The proposed approach proves simple and efficient, particularly for online disentangling vortical and wavy motions of simulated flows. This approach can pave the way for online mixing parameterizations and understanding multiregime and multiscale interactions of oceanic flows.
JOURNAL OF PHYSICAL OCEANOGRAPHY
(2023)
Article
Meteorology & Atmospheric Sciences
Chuanyin Wang, Zhiyu Liu, Hongyang Lin
Summary: A methodology is developed in this study to decompose multiscale oceanic motions based on their respective dynamical characteristics, which is crucial for advancing the interpretation and prediction of oceanic processes. The validity and usefulness of the methodology are demonstrated with a proof-of-concept application to simulated flows in the South China Sea.
JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS
(2023)
Article
Limnology
Zhongwei Yuan, Thomas J. J. Browning, Ruifeng Zhang, Chengwang Wang, Chuanjun Du, Yanmin Wang, Ying Chen, Zhiyu Liu, Xin Liu, Dalin Shi, Minhan Dai
Summary: In nitrogen limited low latitude ocean regions, phosphate depletion can induce stress responses in marine microbes. This study associates a broad region of phosphate depletion in the subtropical North Pacific with different levels of phosphorus stress, and demonstrates the primary nitrogen limitation of the phytoplankton community with the relief provided by aerosol supply. Enhanced alkaline phosphatase activities indicate elevated phosphorus stress in northern sites with depleted phosphate. Increased aerosol deposition, likely stimulated by aerosol iron supply, can drive the regional enhancement in phosphate depletion through elevated nitrogen fixation. These findings are crucial for predicting future biogeochemical responses in the subtropical North Pacific to changes in aerosol supply.
LIMNOLOGY AND OCEANOGRAPHY LETTERS
(2023)
Review
Oceanography
R. Robertson, C. Zhao, W. Wang, Z. Xu, Z. Liu
Summary: Observational data from two areas near the Tiwi Islands and Coburg Peninsula in Australia show that tidal forces dominate the ocean dynamics in these regions. Factors such as solar radiation, convective cooling, wind mixing, and frictional mixing also contribute to the dynamics. However, the dynamics and environments differ between the east and west sides, with the east side being baroclinic and having internal tides, while the west side is barotropic and dominated by tidal advection. The variations in fluorescence and its temporal patterns have important implications for biological activity and primary productivity.
PROGRESS IN OCEANOGRAPHY
(2023)
Review
Oceanography
Qingyou He, Dennis J. McGillicuddy Jr, Xiaogang Xing, Shuqun Cai, Weikang Zhan, Yinghui He, Jiexin Xu, Haigang Zhan
Summary: This study reveals a decoupling between subsurface phytoplankton biomass and surface chlorophyll in cyclonic and anticyclonic eddies in the South Indian Ocean. The cyclonic eddy exhibits a subsurface phytoplankton bloom with a decrease in surface chlorophyll, while the anticyclonic eddy shows homogeneous phytoplankton biomass with a deep mixed layer. This phenomenon is confirmed by global biogeochemical-Argo measurements, highlighting the importance of considering subsurface phytoplankton abundance and productivity in satellite measurements.
PROGRESS IN OCEANOGRAPHY
(2023)
Article
Environmental Sciences
Wenlong Xu, Guifen Wang, Xuhua Cheng, Xiaogang Xing, Jianhuang Qin, Guidi Zhou, Long Jiang, Bingzhang Chen
Summary: In this study, the influence of mesoscale eddies on the subsurface chlorophyll maximum (SCM) layers in the South China Sea was examined using a coupled model. The results showed that eddies play a significant role in shaping the depth, thickness, and magnitude of SCM layers. The effects of eddies on SCM layers are most pronounced near the center of eddies and also influence the phytoplankton community structure.
JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES
(2023)
Article
Multidisciplinary Sciences
Li Liu, Mingming Chen, Xianhui S. Wan, Chuanjun Du, Zhiyu Liu, Zhendong Hu, Zong-Pei Jiang, Kuanbo Zhou, Hongyang Lin, Hui Shen, Duo Zhao, Lanying Yuan, Lei Hou, Jin-Yu T. Yang, Xiaolin Li, Shuh-Ji Kao, Emily J. Zakem, Wei Qin, Minhan Dai, Yao Zhang
Summary: This study found that cyclonic eddies in the western North Pacific subtropical gyre enhance nitrite oxidation and reduce nitrite concentrations in the primary nitrite maximum. The results demonstrate a spatial decoupling of the two steps of nitrification in response to mesoscale processes.
Article
Geosciences, Multidisciplinary
Xiaogang Xing, Peng Xiu, Edward A. Laws, Guo Yang, Xin Liu, Fei Chai
Summary: The dynamics of subsurface chlorophyll maximum depth (zSCM) are mainly driven by light in subtropical gyres, but occasionally display a nutrient-driven pattern when the top of nitracline (znit) becomes shallower than an isolume depth (ziso). This study proposes a two-group competition framework where zSCM is determined by the dominance of nutrient-sensitive picoeukaryotes or light-sensitive Prochlorococcus. This reconciles previous inconsistent conclusions and highlights the importance of the interaction between light and nutrient availability.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Oceanography
Zhongwei Yuan, Thomas J. Browning, Chuanjun Du, Hui Shen, Lei Wang, Yifan Ma, Zong-Pei Jiang, Zhiyu Liu, Kuanbo Zhou, Shuh-Ji Kao, Minhan Dai
Summary: This study investigates the spatial variability, temporal evolution, and impact of mesoscale eddies on upper ocean biogeochemistry in the subtropical Northwest Pacific. The results show that the upper layer of the eddy has lower phosphate concentrations within its core, which can be attributed to elevated N-2 fixation driven by enhanced subsurface iron supply. The presence of eddies affects the phytoplankton biomass in the lower euphotic zone but does not significantly impact the total phytoplankton biomass across the entire euphotic zone. With an anticipated increase in the frequency of cyclonic eddies in the subtropical North Pacific, their role in regulating nutrient biogeochemistry and productivity of the region may become more important.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2023)