Article
Oceanography
Xincheng Zhang, Zhiwei Zhang, James C. McWilliams, Zhongbin Sun, Wei Zhao, Jiwei Tian
Summary: This study focuses on two oppositely rotating submesoscale coherent vortices (SCVs) in the northeastern South China Sea, analyzing their core positions, rotation directions, velocities, etc. It suggests that SCVs may be generated through current-topography interaction and are common in the northeastern South China Sea, potentially providing a novel route for tracer exchange between this region and the western Pacific.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2022)
Article
Geosciences, Multidisciplinary
Yuelin Liu, Xincheng Zhang, Zhongbin Sun, Zhiwei Zhang, Hideharu Sasaki, Wei Zhao, Jiwei Tian
Summary: This study explores the budgets of mesoscale eddy kinetic energy in the northeastern South China Sea and reveals two energy-cascading hotspots, Taiwan southwest and Luzon Strait. The study finds that the dominant source of kinetic energy differs between the two hotspots, with baroclinic conversion being dominant in Taiwan southwest and barotropic conversion and wind stress work being dominant in Luzon Strait. Additionally, submesoscale processes transfer energy reversely to mesoscale eddies, but at lower magnitudes.
JOURNAL OF MARINE SYSTEMS
(2022)
Article
Engineering, Marine
Sang Su Shin, Seo Yeol Choi, Min Ho Seo, Seok Ju Lee, Ho Young Soh, Seok Hyun Youn
Summary: This study sampled planktonic copepods in the northeastern East China Sea to understand the effects of variable water masses on their distribution. The results revealed that different water masses influenced the distribution patterns of copepod species, and several indicator species were identified. The findings highlight the importance of considering water masses when studying species distribution in the area.
JOURNAL OF MARINE SCIENCE AND ENGINEERING
(2022)
Article
Oceanography
Jinchao Zhang, Zhiwei Zhang, Bo Qiu, Xincheng Zhang, Hideharu Sasaki, Wei Zhao, Jiwei Tian
Summary: This study investigates for the first time the seasonal modulation of submesoscale kinetic energy in the northeastern South China Sea using data from a single mooring. The submesoscale kinetic energy shows an asymmetric annual cycle modulated by mixed-layer depth and mesoscale strain rate, and the inverse KE cascade may play a crucial role in modulating mesoscale KE temporal variation in winter.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2021)
Article
Oceanography
Chunhua Qiu, Benjun He, Dongxiao Wang, Zhongshui Zou, Haibo Tang
Summary: This study provides direct observational evidence of submesoscale fronts in the northern South China Sea and their energy sources, improving our understanding of submesoscale processes.
DEEP-SEA RESEARCH PART I-OCEANOGRAPHIC RESEARCH PAPERS
(2023)
Article
Environmental Sciences
Hao Pan, Chunhua Qiu, Hong Liang, Liwei Zou, Ziqi Zhang, Benjun He
Summary: Submesoscale currents in the northern South China Sea are associated with strong vertical velocities and contribute to the redistribution of energy and matter. The submesoscale vertical heat transport (VHT) is significant and varies seasonally, with the largest values observed in the summer and winter in the shelf region and in the winter in open regions. The submesoscale VHT also shows intra-seasonal variations and is influenced by tropical cyclones and the life stages of submesoscale eddies. This study provides valuable insights into submesoscale air-sea interactions and their biological effects.
FRONTIERS IN MARINE SCIENCE
(2023)
Article
Environmental Sciences
Jiannan Wang, Xiaohui Xie, Shaofeng Li, Han Zhang, Wei Li
Summary: Recent mooring observations on the continental slope of the Dongsha Island in the northeastern South China Sea demonstrate the generation of along-slope bottom currents due to the dissipation of obliquely incident internal tides. New mooring data collected on the south side of the island confirms the ability of the previous theory in estimating the along-slope current. Strong near-bottom energy dissipation and a southwestward along-slope current are observed, with the maximum velocity exceeding 6 cm/s.
FRONTIERS IN MARINE SCIENCE
(2023)
Article
Oceanography
Teodor Vrecica, Nick Pizzo, Luc Lenain
Summary: This study provides novel high-resolution airborne remote sensing and in situ observations of wave-current interaction at a submesoscale front near the island of O'ahu, Hawaii. The results show strong modulation of the surface wave field across the frontal boundary, leading to significant spatial inhomogeneities in the wave and wave breaking statistics.
JOURNAL OF PHYSICAL OCEANOGRAPHY
(2022)
Article
Geosciences, Multidisciplinary
Qinbiao Ni, Xiaoming Zhai, Chris Wilson, Changlin Chen, Dake Chen
Summary: An automatic detection method for submesoscale eddies in the South China Sea is developed, revealing their characteristics of an average radius of about 13 km and an aspect ratio of 0.5, with a predominance of cyclones. Additionally, the unique cat's-eye pattern on the surface and the tendency for eddies to become more circular with increasing radius are observed. Submesoscale eddies strongly regulate surface chlorophyll through horizontal advection, while having less coherent signatures in sea surface temperature.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Environmental Sciences
Tran Thi My Hong, Young-Gyu Park, Jun Myoung Choi
Summary: Oceanic mesoscale eddies play a critical role in the transport of mass, heat, salt, carbon, and nutrients in the ocean system. However, current satellite observations are limited in resolving submesoscale processes that contribute to vertical migration and mixing, which are important for phytoplankton in the surface layer. This study utilizes the Geostationary Ocean Color Imager (GOCI) to explore the physical-biological interaction between an anticyclonic mesoscale eddy and a chlorophyll-a secondary bloom in the East/Japan Sea. The results reveal that the bloom coincides with higher divergence and wind-induced Ekman suction in the eddy core.
Article
Environmental Sciences
Jiexia Zhang, Liyang Zhan, Liqi Chen, Haiyan Jin, Man Wu, Wangwang Ye, Jian Liu
Summary: Rapid warming and loss of sea ice in the Arctic Ocean could play an important role in the dissolution and emission of greenhouse gas nitrous oxide (N2O). The northeastern Bering Sea shelf (NEBS) is found to be an important potential source of atmospheric N2O.
Article
Environmental Sciences
Nauzet Hernandez-Hernandez, Yeray Santana-Falcon, Sheila Estrada-Allis, Javier Aristegui
Summary: This study highlights the importance of submesoscale features in impacting the distribution and variability of phytoplankton in the ocean. Observational evidence is lacking for the complexity of short-term phytoplankton distribution and variability, which has been mainly inferred from theoretical and modeling approaches. The results suggest that both temporal and spatial variability may equally contribute to the total variance of picoplankton community in the mixed layer, with time being the principal contributor to variance in the deep chlorophyll maximum (DCM).
FRONTIERS IN MARINE SCIENCE
(2021)
Article
Multidisciplinary Sciences
Agnieszka Herman, Jan Marcin Weslawski
Summary: Surface waters of the oceans carry a variety of materials, and their transport and distribution depend on properties and dynamical processes. Research efforts have been invested in observations and modeling of ocean material transport, especially in the context of marine plastic pollution. This study analyzed typical and anomalous transport pathways of surface-floating particles in the northern North Atlantic and the Arctic Ocean using numerical simulations. The study highlighted the important role of wave-induced currents and the influence of seasonal variability and anomalous atmospheric circulation on material transport.
SCIENTIFIC REPORTS
(2022)
Article
Environmental Sciences
Yury Yu Yurovsky, Arseny A. Kubryakov, Evgeny Plotnikov, Pavel N. Lishaev
Summary: This study uses a commercial unmanned aerial vehicle (UAV) to estimate coastal submesoscale currents and validates the consistency between the results obtained using wave dispersion analysis (WDA) and 4D-variational assimilation (4DVAR). The error caused by uncontrolled UAV motions is assessed by referencing to static land control points.
Article
Oceanography
Chunhua Qiu, Zihao Yang, Dongxiao Wang, Ming Feng, Jingzhi Su
Summary: This study investigates the characteristics of submesoscale ageostrophic motion in the South China Sea using surface drifters and satellite altimeter data. The results show that this motion enhances the strength of mesoscale eddies and plays a significant role in their development.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2022)
Article
Geosciences, Multidisciplinary
Akira Kuwano-Yoshida, Hideharu Sasaki, Yoshikazu Sasai
GEOPHYSICAL RESEARCH LETTERS
(2017)
Article
Geosciences, Multidisciplinary
H. Sasaki, S. Kida, R. Furue, M. Nonaka, Y. Masumoto
GEOPHYSICAL RESEARCH LETTERS
(2018)
Article
Multidisciplinary Sciences
Qingxuan Yang, Maxim Nikurashin, Hideharu Sasaki, Hui Sun, Jiwei Tian
SCIENTIFIC REPORTS
(2019)
Article
Oceanography
Shinichiro Kida, Kelvin J. Richards, Hideharu Sasaki
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2019)
Article
Oceanography
Qingye Wang, Xin Yuan, Dunxin Hu, Hideharu Sasaki
Summary: The study of intraseasonal variability in the Kuroshio east of Taiwan reveals complex dynamics influenced by various factors such as ocean eddies, surface eddies, and coastal cold water upwelling. Ocean eddies southeast of Taiwan have a significant impact on the intraseasonal variability in the Kuroshio.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2021)
Article
Oceanography
Yang Yang, X. San Liang, Hideharu Sasaki
Summary: In this study, the different peaks in the power spectrum of the upper and deep parts of the Kuroshio Extension are investigated using outputs from an ocean general circulation model. The primary driver of deep intraseasonal variability is found to be vertical pressure work, leading to the transport of intraseasonal kinetic energy to the deep layer. Upward and downward fluxes of intraseasonal kinetic energy are observed, with the accumulated upstream kinetic energy advecting eastward and forming the primary source of kinetic energy variability in the downstream Kuroshio Extension.
Article
Oceanography
Jinchao Zhang, Zhiwei Zhang, Bo Qiu, Xincheng Zhang, Hideharu Sasaki, Wei Zhao, Jiwei Tian
Summary: This study investigates for the first time the seasonal modulation of submesoscale kinetic energy in the northeastern South China Sea using data from a single mooring. The submesoscale kinetic energy shows an asymmetric annual cycle modulated by mixed-layer depth and mesoscale strain rate, and the inverse KE cascade may play a crucial role in modulating mesoscale KE temporal variation in winter.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2021)
Article
Geosciences, Multidisciplinary
Hideharu Sasaki, Bo Qiu, Patrice Klein, Masami Nonaka, Yoshikazu Sasai
Summary: Recent studies have reported the impacts of oceanic submesoscale circulations on oceanic circulation, marine ecosystem, and air-sea heat flux. This study shows the interannual variations of active submesoscale circulations in winter and their mechanism in the subtropical northeastern Pacific. The submesoscale kinetic energy varies synchronously with the available potential energy release in a process of mixed layer instability (MLI), and El Nino events appear to modulate the interannual variations.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Oceanography
Yang Ding, Lixiao Xu, Shang-Ping Xie, Hideharu Sasaki, Zhengguang Zhang, Haijin Cao, Yang Zhang
Summary: In the mid-latitude North Pacific, the winter ocean heat loss reaches its maximum in the Kuroshio-Oyashio Extension (KOE) region. However, the observed shallow mixed layer depth (MLD) there, flanked by deep MLD on either side, is not reproduced by coarse-resolution or mesoscale eddy-resolving models. This study shows that the shallow MLD in the KOE region is closely related to submesoscale frontal dynamics, where the geostrophic strain rate and surface buoyancy loss during winter play important roles.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2022)
Article
Geosciences, Multidisciplinary
Tomoki Tozuka, Yoshikazu Sasai, Sayaka Yasunaka, Hideharu Sasaki, Masami Nonaka
Summary: Decadal variations of phytoplankton concentration in the upstream Kuroshio Extension region are investigated using an ecosystem model embedded in an eddy-resolving ocean general circulation model. The study finds that the anomalies of phytoplankton biomass distribution are influenced by the transitions between stable and unstable states of the Kuroshio Extension.
PROGRESS IN EARTH AND PLANETARY SCIENCE
(2022)
Article
Oceanography
Mochamad Riza Iskandar, Yanli Jia, Hideharu Sasaki, Ryo Furue, Shinichiro Kida, Toshio Suga, Kelvin J. Richards
Summary: Previous studies have indicated the significant impact of mesoscale eddy activities on the transport and water mass properties of the Indonesian Throughflow (ITF). This study investigates the effects of these eddy activities, or high-frequency flow variability (HFFV), on the residence time and pathway of the ITF. The results reveal contrasting circulation characteristics in the Sulawesi and Banda Seas, with higher HFFV in the former and minimal effects on the ITF in the latter.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2023)
Article
Ecology
Yoshikazu Sasai, Sherwood Lan Smith, Eko Siswanto, Hideharu Sasaki, Masami Nonaka
Summary: Phytoplankton growth and biomass are influenced by changes in light and nutrient availability. Existing photoacclimation models have not been fully applied and tested against the observed flexible response of phytoplankton communities. This study compares different models and finds that a flexible phytoplankton functional type model performs better in certain cases.
Article
Physics, Fluids & Plasmas
Hideharu Sasaki, Bo Qiu, Patrice Klein, Yoshikazu Sasai, Masami Nonaka
Article
Geosciences, Multidisciplinary
Hideharu Sasaki, Shinichiro Kida, Ryo Furue, Hidenori Aiki, Nobumasa Komori, Yukio Masumoto, Toru Miyama, Masami Nonaka, Yoshikazu Sasai, Bunmei Taguchi
GEOSCIENTIFIC MODEL DEVELOPMENT
(2020)