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Spatiotemporal structures of tidal currents and upwelling around the Hachiri-ga-se marine hill in the southwestern Japan Sea J. Oceanogr. (IF 1.469) Pub Date : 2021-01-15 Tetsutaro Takikawa, Toshimitsu Goto, Akira Hamano, Takeshi Nakamura
Spatiotemporal structures of tidal and mean currents in August 2008 and May 2010 were estimated by shipboard ADCP data around the Hachiri-ga-se marine hill in the southwestern Japan Sea. The time variations of the tidal currents were quite similar both in August and May. The vertical structure of tidal and mean currents in August was more baroclinic than that in May. Upwelling region moved when the
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Seasonal variations in salinity of the North Pacific Intermediate Water and vertical mixing intensity over the Okinawa Trough J. Oceanogr. (IF 1.469) Pub Date : 2021-01-12 Hirohiko Nakamura, Ryuichiro Inoue, Ayako Nishina, Toshiya Nakano
Seasonal variations in vertical mixing intensity in the intermediate layer of the northern Okinawa Trough was deduced using the seasonal variations in salinity in the North Pacific Intermediate Water (NPIW) using two distinct datasets: the World Ocean Atlas 2013 and historical conductivity, temperature, and depth data in the Okinawa Trough. Water mass analysis of the NPIW with a simple advection model
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Enhanced vertical turbulent nitrate flux in the intermediate layer of the Kuroshio in the Tokara Strait J. Oceanogr. (IF 1.469) Pub Date : 2021-01-12 T. Tanaka, D. Hasegawa, I. Yasuda, D. Yanagimoto, S. Fujio, H. Nakamura, R. Inoue, J. Nishioka
Vertical mixing in the ocean is an important physical process that brings deep nutrients to the upper layer. The Tokara Strait, where the Kuroshio flows out to the North Pacific from the East China Sea, is known for a mixing hotspot, but the associated vertical nutrient transport has not been well quantified yet, especially in the intermediate layer below 200 m depth. This study involved flow, turbulence
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Role of tide-induced vertical mixing in the deep Pacific Ocean circulation J. Oceanogr. (IF 1.469) Pub Date : 2021-01-12 Takao Kawasaki, H. Hasumi, Y. Tanaka
We investigate the control mechanisms of the deep Pacific Ocean circulation by introducing updated methods for parameterizing tidal mixing. The column-integrated rates of dissipation in near- and far-fields are derived from the tidal energy conversion and dissipation rates estimated by a high resolution tide model. In the calculation of the far-field mixing, its dependency on stratification is taken
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Elevated turbulent and double-diffusive nutrient flux in the Kuroshio over the Izu Ridge and in the Kuroshio Extension J. Oceanogr. (IF 1.469) Pub Date : 2021-01-11 Takeyoshi Nagai, Gandy Maria Rosales Quintana, Gloria Silvana Durán Gómez, Fuminori Hashihama, Kosei Komatsu
While the Kuroshio is known to be a nutrient stream, as these nutrients are in dark subsurface layers, they are not immediately available for photosynthesis unless they are supplied to the sunlit surface layers. Recent microstructure observations have revealed that strong diapycnal mixing caused by the Kuroshio flowing over topographic features and double diffusion in the subsurface layers of the Kuroshio
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Vertical eddy diffusivity in the subsurface pycnocline across the Pacific J. Oceanogr. (IF 1.469) Pub Date : 2021-01-09 S. Itoh, H. Kaneko, S. Kouketsu, T. Okunishi, E. Tsutsumi, H. Ogawa, I. Yasuda
In the stratified ocean, vertical eddy diffusivity in the subsurface pycnocline plays a major role in new production through transporting nutrients upwards from the darker/nutrient-rich layer. In order to evaluate the diffusivity that was less available in the subsurface layers where indirect estimations are difficult, we conducted direct microstructure measurements in the upper 300 m of the open Pacific
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Internal hydraulic jump in the Tsugaru Strait J. Oceanogr. (IF 1.469) Pub Date : 2021-01-08 T. Tanaka, D. Hasegawa, T. Okunishi, H. Kaneko, T. Ono
Sea straits are known for important sites to modify water-mass properties and transport nutrients through vigorous vertical mixing. The first microstructure measurements ever taken in the Tsugaru Strait, between the Sea of Japan and the Northwest Pacific Ocean, showed elevated turbulent mixing. The turbulent energy dissipation rate was especially enhanced to O(10−6 W kg−1) via an internal hydraulic
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Ocean state estimations for synthesis of ocean-mixing observations J. Oceanogr. (IF 1.469) Pub Date : 2021-01-07 Shuhei Masuda, Satoshi Osafune
Vertical mixing in oceans is an essential component of the dynamics of ocean circulation, including meridional circulation. Nevertheless, various aspects of mixing, particularly in conjunction with global ocean energetics, remain debatable. One of the biggest reasons is the lack of observational facts. With the recent expansion of global vertical-mixing observations, attempts have been made to estimate
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Vertical turbulent nitrate flux from direct measurements in the western subarctic and subtropical gyres of the North Pacific J. Oceanogr. (IF 1.469) Pub Date : 2021-01-06 Hitoshi Kaneko, Ichiro Yasuda, Sachihiko Itoh, Shin-ichi Ito
Vertical turbulent nitrate fluxes were estimated in the western North Pacific from direct measurements of vertical turbulent mixing and vertically continuous nitrate profiles during the summer of 2008. We made three north–south transects that covered the area from the subarctic to the subtropics including a section along the Emperor Sea Mounts. Subsurface fluxes generally showed an increasing trend
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Mesoscale-dependent near-inertial internal waves and microscale turbulence in the Tsushima Warm Current J. Oceanogr. (IF 1.469) Pub Date : 2021-01-06 Yusuke Kawaguchi, Taku Wagawa, Itsuka Yabe, Daiki Ito, Tomoharu Senjyu, Sachihiko Itoh, Yosuke Igeta
This study examined characteristics of near-inertial internal waves (NIWs) associated with the background mesoscale field near the Tsushima Warm Current. Observational stations off Sado Island were visited recurrently to assess spatiotemporal changes of fine-scale and microscale properties of seawater. Also, NIWs were inspected in terms of relative vorticity and total strain in surface geostrophic
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Observations of anticyclonic eddies in the western subarctic North Pacific J. Oceanogr. (IF 1.469) Pub Date : 2021-01-06 Ryo Dobashi, Hiromichi Ueno, Yuki Okada, Takahiro Tanaka, Jun Nishioka, Toru Hirawake, Atushi Ooki, Sachihiko Itoh, Daisuke Hasegawa, Yoshikazu Sasai, Hideharu Sasaki, Ichiro Yasuda
We conducted a ship observation of two anticyclonic mesoscale eddies (Eddies A and B) between June and July 2016 in the offshore region of the western subarctic North Pacific to clarify the impact of anticyclonic eddies on biological production. Analysis of satellite data reveals that Eddy A formed south of the Alaskan Peninsula on May 2011 while Eddy B formed in the observation area on November 2015
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Estimate of turbulent energy dissipation rate using free-fall and CTD-attached fast-response thermistors in weak ocean turbulence J. Oceanogr. (IF 1.469) Pub Date : 2021-01-05 Ichiro Yasuda, Shinzou Fujio, Daigo Yanagimoto, KeungJong Lee, Yusuke Sasaki, Shuo Zhai, Mamoru Tanaka, Sachihiko Itoh, Takahiro Tanaka, Daisuke Hasegawa, Yasutaka Goto, Daisuke Sasano
The measurement of turbulence is necessary to quantify the vertical, diapycnal transport of heat, water and substances influencing climate, nutrient supply and marine ecosystems. As specialist instrumentation and ship-time are required to conduct microstructure measurements to quantify turbulence intensity, there is a need for more inexpensive and easy measurement methods. This study demonstrated that
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Effects of eddies on the subduction and movement of water masses reaching the $$137^{\circ }\,\hbox {E}$$ 137 ∘ E section using Lagrangian particles in an eddy-resolving OGCM J. Oceanogr. (IF 1.469) Pub Date : 2021-01-03 Hideyuki Nakano, Yoshimasa Matsumura, Hiroyuki Tsujino, Shogo Urakawa, Kei Sakamoto, Takahiro Toyoda, Goro Yamanaka
The effects of eddies on the subduction and movement of water masses reaching the 137\(^{\circ }\) E section are examined in a nominal 10-km resolution ocean general circulation model using a backward-particle tracking method. Target water masses are the Tropical Water (TW), the Eastern Subtropical Mode Water (ESTMW), the Subtropical Mode Water (STMW), and lighter variety of the Central Mode Water
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Phytoplankton growth and grazing mortality through the oligotrophic subtropical North Pacific J. Oceanogr. (IF 1.469) Pub Date : 2021-01-01 Siyu Jiang, Fuminori Hashihama, Hiroaki Saito
The subtropical North Pacific has been historically considered as a stable and homogenous oligotrophic marine ecosystem. The consistently low phytoplankton biomass has been attributed to a close balance between phytoplankton growth and grazing mortality. However, phytoplankton summer blooms were frequently observed in the central North Pacific near the Hawaiian Islands. To determine whether this is
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Decadal-scale variability of the North Pacific subtropical mode water and its influence on the pycnocline observed along 137°E J. Oceanogr. (IF 1.469) Pub Date : 2020-11-28 Fumiaki Kobashi, Toshiya Nakano, Naoto Iwasaka, Tomomichi Ogata
Decadal-scale variability of the North Pacific subtropical mode water (STMW) and its influence on the pycnocline are examined by analyzing Japan Meteorological Agency (JMA) repeat hydrographic observations along the 137°E meridian from 1972 to 2019, with a particular focus on the summer season when the seasonal upper pycnocline develops above the STMW. The STMW appears between 20° and 32°N at 137°E
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Distribution and stoichiometry of Al, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb in the East China Sea J. Oceanogr. (IF 1.469) Pub Date : 2020-11-23 Yuzuru Nakaguchi, Yoshinori Ikeda, Atsushi Sakamoto, Linjie Zheng, Tomoharu Minami, Yoshiki Sohrin
The dissolved (d) and total dissolvable (td) trace metals were determined in seawater samples collected from the East China Sea (ECS). Labile particulate (lp) species was calculated as td minus d, and the sectional and vertical distributions of d and lp trace metals were evaluated. The surface concentrations of dAl, dCo, dNi, dCu, and dPb were higher in the continental shelf region than in the Kuroshio
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Global trends of ocean CO 2 sink and ocean acidification: an observation-based reconstruction of surface ocean inorganic carbon variables J. Oceanogr. (IF 1.469) Pub Date : 2020-11-18 Yosuke Iida, Yusuke Takatani, Atsushi Kojima, Masao Ishii
Ocean acidification is likely to impact marine ecosystems and human societies adversely and is a carbon cycle issue of great concern. Projecting the degree of ocean acidification and the carbon-climate feedback will require understanding the current status, variability, and trends of ocean inorganic carbon system variables and the ocean carbon sink. With this goal in mind, we reconstructed total alkalinity
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Unusually high sea level at the south coast of Japan in September 2011 induced by the Kuroshio J. Oceanogr. (IF 1.469) Pub Date : 2020-11-09 Norihisa Usui, Koji Ogawa, Kei Sakamoto, Hiroyuki Tsujino, Goro Yamanaka, Tsurane Kuragano, Masafumi Kamachi
Using a coastal assimilation model, generation mechanism of unusually high sea level (UHSL) at the south coast of Japan in September 2011 is investigated. Both model results and tide gauge observations indicate that sea level rise associated with the UHSL event occurred twice in the middle and end of September. The first one, which is localized around the eastern part of the Seto Inland Sea, is caused
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Rapid freshening of Japan Sea Intermediate Water in the 2010s J. Oceanogr. (IF 1.469) Pub Date : 2020-10-22 Naohiro Kosugi, Nariaki Hirose, Takahiro Toyoda, Masao Ishii
Japan Sea Intermediate Water (JSIW) is in the salinity-minimum layer present between the thermocline and deep water in the Japan Sea. Annual shipboard measurements over the past 20 years revealed that JSIW rapidly freshened in the 2010s, particularly from 2010 to 2011, from 2012 to 2013, and from 2015 to 2016. The mean rate of salinity change at σθ = 27.16 kg m−3 (σθ indicates potential density minus
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Effect of diatom abundance and biogenic silica availability on the population growth of tintinnid ciliates at Suruga Bay J. Oceanogr. (IF 1.469) Pub Date : 2020-10-21 Nhan Van Dinh, Beatriz E. Casareto, Mohan P. Niraula, Keita Toyoda, Aussanee Meekaew, Yoshimi Suzuki
The effects of diatom abundance and biogenic silica (BSi) deposition on the population growth of tintinnid ciliates were investigated using incubations of sub-surface waters (10 m depth) of Suruga Bay, Japan in April and November 2018. Seawater for incubation was pre-filtered using a 200-µm mesh to remove mesozooplankton grazers. Initial concentrations of dissolved inorganic nitrogen were similar in
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Wavenumber spectra of the chlorophyll “a” concentration and the sea surface temperature in the area of the anticyclonic eddy in the South China Sea J. Oceanogr. (IF 1.469) Pub Date : 2020-09-20 T. I. Kleshcheva, M. S. Permyakov, P. A. Salyuk, I. A. Golik
The wavenumber spectra of the chlorophyll “a” concentration (Chla) and the sea surface temperature (SST) were obtained from the data of the shipborne fluorometer and satellite measurements in the area of the anticyclonic eddy in the South China Sea in February—March 2004. In the southwestern part of the eddy, the slope of SST spectrum, received from the ship data was − 2.6 ± 0.1 at scales of 3–110 km
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Correction to: Spatial and temporal scales of sea surface salinity in the tropical Indian Ocean from SMOS, Aquarius and SMAP J. Oceanogr. (IF 1.469) Pub Date : 2020-09-19 Senliang Bao, Huizan Wang, Ren Zhang, Hengqian Yan, Jian Chen
The original article can be found online.
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Space–time variations of sea ice in Bohai Sea in the winter of 2009–2010 simulated with a coupled ocean and ice model J. Oceanogr. (IF 1.469) Pub Date : 2020-09-11 Rui Li, Youyu Lu, Xianmin Hu, Donglin Guo, Peng Zhao, Ning Wang, Kenneth Lee, Baiyu Zhang
Sea ice variations in the severe winter of 2009–2010 in the Bohai Sea are simulated with a coupled ocean and ice model. The modelled ice coverage shows good agreement with satellite observations. Integrated over three sub-regions [the extended Liaodong Bay (LDB), Bohai Bay, and Laizhou Bay], the temporal variations of ice volume and surface air temperature are well correlated at time scales of 5–15 days
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Diel vertical migration promotes zooplankton horizontal patchiness J. Oceanogr. (IF 1.469) Pub Date : 2020-09-10 Bingzhang Chen, Eiji Masunaga, Sherwood Lan Smith, Hidekatsu Yamazaki
Spatial patchiness of plankton enhances fishery production and carbon export in the ocean. While diel vertical migration (DVM) has been identified as an important factor contributing to vertical patchiness, its effect on horizontal patchiness has never been investigated. We use a simple individual-based zooplankton model to examine the effect of DVM on the horizontal patchiness of four zooplankton
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Further correcting pressure effects on SBE911 CTD-conductivity data from hadal depths J. Oceanogr. (IF 1.469) Pub Date : 2020-09-09 Hans van Haren, Hiroshi Uchida, Daigo Yanagimoto
Hadal, > 6000 m deep shipborne Sea-Bird Electronics SBE 911plus Conductivity Temperature Depth (CTD) data are obtained using two different systems in the vicinity of the Earth’s deepest point, in the Challenger Deep, Mariana Trench 14 years apart. Below 7000 m in very weakly density stratified waters, the salinity data from both sets show an artificial increase with depth of about 10–6 g kg−1 m−1 that
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Nutrient and dissolved inorganic carbon variability in the North Pacific J. Oceanogr. (IF 1.469) Pub Date : 2020-09-05 Sayaka Yasunaka, Humio Mitsudera, Frank Whitney, Shin-ichiro Nakaoka
A compilation of surface water nutrient (phosphate, nitrate, and silicate) and partial pressure of CO2 (pCO2) observations from 1961 to 2016 reveals seasonal and interannual variability in the North Pacific. Nutrients and calculated dissolved inorganic carbon (DIC) reach maximum concentrations in March and minimum in August. Nutrient and DIC variability is in-phase (anti-phase) with changes in the
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Increasing trend in Japan Sea Throughflow transport J. Oceanogr. (IF 1.469) Pub Date : 2020-09-01 Shinichiro Kida, Katsumi Takayama, Yoshi N. Sasaki, Hiromi Matsuura, Naoki Hirose
A long-term increasing trend in the transport of the Japan Sea Throughflow is observed from sea-level differences across the Tsushima Strait. Tidal gauge observations show sea level at Hakata, Japan, increasing at a higher rate than that at Busan, Korea. Numerical modeling results suggest that this increasing trend is forced by a northward shift in the Kuroshio axis. As the Kuroshio axis moves northward
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Spatial downscaling of MODIS Chlorophyll-a with machine learning techniques over the west coast of the Yellow Sea in South Korea J. Oceanogr. (IF 1.469) Pub Date : 2020-08-29 Hamid Mohebzadeh, Taesam Lee
Effective water quality monitoring of coastal areas through the measurement of Chlorophyll-a (Chl-a) has remarkably progressed by ocean color remote sensing. Among different sensors, Moderate Resolution Imaging Spectroradiometer (MODIS) Level 3 products provide reliable global representations of the Chl-a concentration. On the other hand, due to the coarse spatial resolution of MODIS data, its applicability
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Observation of the deep Indonesian throughflow using helium isotopes J. Oceanogr. (IF 1.469) Pub Date : 2020-08-11 Ma. Teresa Escobar, Naoto Takahata, Hajime Obata, Yuji Sano
Helium isotopes in the ocean are very useful tracers of hydrothermal input and deep-sea circulation. Unlike labile trace elements, noble gases are inert and do not react with other substances in the water column. Previous studies in the Indian Ocean showed that helium isotopes in the region were discharged mainly from the central Indian midocean ridge, convergent boundaries, and the Pacific Ocean via
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Heat and salinity transport between the permanent pycnocline and the mixed layer due to the obduction process evaluated from a gridded Argo dataset J. Oceanogr. (IF 1.469) Pub Date : 2020-08-09 Yoshimi Kawai, Shigeki Hosoda, Kazuyuki Uehara, Toshio Suga
It is necessary for air–sea interaction and climate research to evaluate heat and salinity transport between the mixed layer (ML) and the permanent pycnocline and its contribution to the ML properties. The authors have calculated the obduction and subduction rates with the Eulerian definition using a 1°-grid Argo dataset and incorporated the obduction rate into the ML budget analysis in order to assess
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Horizontal distribution of nematode communities in a seasonally-hypoxic enclosed sea (Omura Bay, Japan) J. Oceanogr. (IF 1.469) Pub Date : 2020-07-22 Quyen T. D. Nguyen, Dongsung Kim, Motohiro Shimanaga, Jun Uchida, Takashi Aoshima, Minoru Wada
Habitat heterogeneity is one of the major factors shaping community structure and diversity of many fauna. The present study aimed to reveal the influence of habitat heterogeneity on the nematode community structures and diversity in a seasonally hypoxic bay (Omura Bay of Nagasaki in Western Kyushu, Japan). The severity of hypoxia varies typically along north–south axis of the bay, which is intensified
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Significant wave height retrieval from Sentinel-1 SAR imagery by convolutional neural network J. Oceanogr. (IF 1.469) Pub Date : 2020-07-15 Sihan Xue, Xupu Geng, Xiao-Hai Yan, Ting Xie, Qiuze Yu
Significant wave height (SWH) is an important wave parameter that is related to near-shore activities and research on the phenomenon near the air-sea interface. Here, we proposed a new method for retrieving SWH from C-band Sentinel-1 synthetic aperture radar (SAR) interferometric wide mode data based on convolutional neural network (CNN), which can directly establish the empirical relationship between
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On the extremization of wave energy dissipation rates in equilibrium beach profiles J. Oceanogr. (IF 1.469) Pub Date : 2020-07-01 Valerio Faraoni
Equilibrium beach profiles are explained in the context of a thermodynamic theory in which energy dissipation rate due to shoaling waves is extremized through a variational principle. The issue of whether this extremum corresponds to a maximum or a minimum of the action integral under the assumptions made is answered by computing the second variation of the integral around the equilibrium profile:
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Simulating tropical cyclone waves in the East China Sea with an event-based, parametric-adjusted model J. Oceanogr. (IF 1.469) Pub Date : 2020-06-24 Xuan Wang, Chenyang Yao, Guoping Gao, Haoyu Jiang, Dali Xu, Ge Chen, Zhao Zhang
Parametric cyclone wind models with storm characteristics derived from statistical representation do not agreeably delineate the wind field in the East China Sea, leading to uncertain errors in the numerical simulations of Typhoon waves. A new approach to adjust the cyclone wind field in the framework of the Holland model is proposed. The radius of maximum wind speed and the logarithmically varied
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Annual versus semi-annual eddy kinetic energy variability in the Celebes Sea J. Oceanogr. (IF 1.469) Pub Date : 2020-06-22 Chengcheng Yang, Xiao Chen, Xuhua Cheng, Bo Qiu
Eddy kinetic energy (EKE) in the Celebes Sea (CS) is investigated using a global, eddy-resolving, ocean general circulation model (OGCM) output. The OGCM simulation shows that a strong EKE is confined in the upper 300-m layer. The period of EKE variability varies with depth. In the 0–100-m layer, EKE has a distinct annual cycle that is strong in winter (December–February) and weak in summer (June–August)
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Comparison of the third-generation Japanese ocean flux data set J-OFURO3 with numerical simulations of Typhoon Dujuan (2015) traveling south of Okinawa J. Oceanogr. (IF 1.469) Pub Date : 2020-06-12 Akiyoshi Wada, Hiroyuki Tomita, Shin’ichiro Kako
Insufficient in situ observations in high winds make it difficult to verify climatological data sets and the results of tropical cyclone (TC) simulations. Reliable data sets are necessary for developing numerical models that predict TCs more accurately. This study attempted to compare the third-generation Japanese Ocean Flux Data Sets with Use of Remote-Sensing Observations (J-OFURO3) data, with TC
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Spatial and temporal scales of sea surface salinity in the tropical Indian Ocean from SMOS, Aquarius and SMAP J. Oceanogr. (IF 1.469) Pub Date : 2020-06-12 Senliang Bao; Huizan Wang; Ren Zhang; Hengqian Yan; Jian Chen
The spatial and temporal decorrelation scales of sea surface salinity (SSS) have been calculated in the tropical Indian ocean from the satellite measurements including Soil Moisture and Ocean Salinity (SMOS), Aquarius, Soil Moisture Active Salinity (SMAP), and the model output data for the period of 2011–2017. The differences in spatial and temporal scales from different products are discussed and
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Formation of Central Mode Water based on two zonal hydrographic sections in spring 2013 and 2016 J. Oceanogr. (IF 1.469) Pub Date : 2020-05-29 Eitarou Oka; Shinya Kouketsu; Daigo Yanagimoto; Daiki Ito; Yoshimi Kawai; Shusaku Sugimoto; Bo Qiu
Two zonal high-density hydrographic sections along 41° N and 37.5° N east of Japan were occupied in April 2013 and June 2016 to examine the formation of Central Mode Water (CMW) and Transition Region Mode Water (TRMW) in relation to fronts and eddies. In the 41° N section traversing the meandering subarctic front, the denser variety of CMW (D-CMW) and TRMW was formed continuously on both sides of the
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Continuous winter oceanic profiling in the Cape Darnley Polynya, East Antarctica J. Oceanogr. (IF 1.469) Pub Date : 2020-05-25 Shigeru Aoki; Kazuya Ono; Daisuke Hirano; Takeshi Tamura
Antarctic coastal polynyas provide extremely dense water to the global abyss, but the dense water formation process has been poorly monitored in winter. This study developed a new tethered profiler to realize time-series observations of the water column in the Cape Darnley Polynya, East Antarctica. The system successfully obtained temperature and salinity profiles at 10-day intervals from March to
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Distribution, biomass, and species composition of salps and doliolids in the Oyashio–Kuroshio transitional region: potential impact of massive bloom on the pelagic food web J. Oceanogr. (IF 1.469) Pub Date : 2020-05-19 Nurul Huda Ahmad Ishak; Kazuaki Tadokoro; Yuji Okazaki; Shigeho Kakehi; Satoshi Suyama; Kazutaka Takahashi
The Oyashio–Kuroshio Transitional Region (OKTR) is a nursery ground for pelagic fishes; thus, community succession of mesozooplankton is pivotal to understand prey availability, and it subsequently affects recruitment success. We investigated the surface distribution, biomass, and species composition of thaliaceans (salps and doliolids) that potentially have a significant impact on the food web and
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Sex ratio of Stygiopontius senokuchiae (Dirivultidae, Copepoda), an endemic copepod species at deep hydrothermal vent sites, is biased to males J. Oceanogr. (IF 1.469) Pub Date : 2020-04-23 Reina Senokuchi; Hidetaka Nomaki; Daisuke Uyeno; Hiromi Kayama Watanabe; Tomo Kitahashi; Motohiro Shimanaga
Stygiopontius copepods (Dirivultidae, Siphonostomatoida, Crustacea) are among the most successful meiobenthic organisms at deep-sea hydrothermal vents. Most of their ecology is not yet known, including the spatiotemporal differences in their sex ratios and their controlling factors. We investigated spatial variation in the sex ratio of adult Stygiopontius senokuchiae and its association with environmental
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Spatial and seasonal variability of surface particulate inorganic carbon and relationship with particulate organic carbon in the Yellow-Bohai Sea J. Oceanogr. (IF 1.469) Pub Date : 2020-04-16 Xiujun Wang; Jun Yu; Hang Fan
Particulate carbon is one of the major carbon forms in seawater, thus plays an important role in the carbon cycle. Limited small scale studies showed that particulate inorganic carbon (PIC) content was much higher than particulate organic carbon (POC) in the Yellow River Estuary. This study is to test the hypothesis that surface PIC is significantly higher than POC in the Yellow-Bohai Sea (YBS). Using
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Tidal velocities on the Mid-Atlantic Bight continental shelf using high-frequency radar J. Oceanogr. (IF 1.469) Pub Date : 2020-03-30 K. Brunner; K. M. M. Lwiza
Surface current velocity from high-frequency radar data are used to study tidal currents in the Mid-Atlantic Bight, which represent an average 32% of the total kinetic energy of the surface circulation. Average annual and seasonal tidal current characteristics and the associated variance of the semi-major axis are computed. The M2 constituent dominates the tide, representing a maximum of 72.26% and
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The effect of background flow shear on the topographic Rossby wave J. Oceanogr. (IF 1.469) Pub Date : 2020-03-27 YunLong Shi; DeZhou Yang; BaoShu Yin
Due to the ubiquitous steep continental shelf slope in the East China Sea, topographic Rossby waves are very common when the Kuroshio Current flows along the slope, and of great importance in the water and energy exchange between the open ocean and coastal sea. To examine the structural characteristics of topographic Rossby wave, we use stretching transform of time and space and perturbation method
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Response of the Kuroshio east of Taiwan to mesoscale eddies and upstream variations J. Oceanogr. (IF 1.469) Pub Date : 2020-03-17 Vigan Mensah; Sen Jan; Magdalena Andres; Ming-Huei Chang
Two-years of data from an array of pressure-sensor equipped inverted echo sounders (PIESs) deployed across the Kuroshio east of Taiwan are analyzed in this study. Cross sections of temperature, absolute, barotropic and baroclinic velocities, as well as time series of volume transports and maximum velocity axis location are analyzed to better understand the response of the Kuroshio to local arrivals
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Past and lost influence of the Kuroshio on estuarine recruitment of Anguilla japonica glass eels J. Oceanogr. (IF 1.469) Pub Date : 2020-03-07 Yoichi Miyake; Marie-Agnès Tellier; Aigo Takeshige; Hikaru Itakura; Akira Yoshida; Shingo Kimura
The present study aims to reveal the influence of path fluctuations of the western boundary current (Kuroshio) and other regional environmental factors on coastal recruitment of transported organisms. As a model species, we chose a catadromous eel species, Japanese eel Anguilla japonica, which is transported poleward by the Kuroshio in early life stages. We analyzed a 50-year record of A. japonica
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Analyzing dynamic characteristics of river plume in the Modaomen mouth, Pearl River estuary J. Oceanogr. (IF 1.469) Pub Date : 2020-02-17 Jie Ren; Wei Li; Yazhou Gao
River plumes are an important component of estuarine circulation and have a vital role in the transport of estuarine material and momentum balance. However, little information is available on the influence of mouth bars on estuarine plumes. To address this, momentum balance analysis was carried out using the ocean numerical model, to analyze the dynamic characteristics of the Pearl River plumes. The
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Seasonal dynamics of seawater CO 2 system at a coastal site near the southern tip of Izu Peninsula, Japan J. Oceanogr. (IF 1.469) Pub Date : 2020-02-17 Shigeki Wada; Masao Ishii; Naohiro Kosugi; Daisuke Sasano; Wakana Matsushita; Yuko Omori; Takeo Hama
To elucidate how variables of the seawater CO2 system in surface waters have been changing seasonally and the mechanisms responsible for these changes in the area off the south coast of central Honshu Island, Japan, we made time-series measurements of total dissolved inorganic carbon (DIC), total alkalinity (TA), inorganic macronutrient and chlorophyll a concentrations as well as temperature and salinity
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The response of surface chlorophyll to mesoscale eddies generated in the eastern South China Sea J. Oceanogr. (IF 1.469) Pub Date : 2020-02-03 Jin Liu; Yuntao Wang; Yeping Yuan; Dongfeng Xu
This study investigates the response of surface chlorophyll (CHL) to mesoscale eddies generated in the eastern South China Sea (ESCS) during their lifecycles based on global eddy dataset and chlorophyll data from January 2003 to December 2016. The results show that the responses of CHL anomalies to cyclones are stronger than anticyclones generated in the Luzon Strait (LS) and in the area off northwest
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Enhancement of Zhe-Min coastal water in the Taiwan Strait in winter J. Oceanogr. (IF 1.469) Pub Date : 2020-01-24 Caiyun Zhang; Yan Huang; Wenxiang Ding
The cold, low-salinity, and nutrient-rich Zhe-Min Coastal Water (ZMCW), an important part of the China Coastal Current, plays a key role in the hydrodynamics, biogeochemical processes and marine ecosystem in the Taiwan Strait (TWS). In this study, the long-term characteristics of the ZMCW were investigated using available data sets, including merged satellite-derived sea surface temperature (SST) data
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Aggregation of marine organic matter by bubbling J. Oceanogr. (IF 1.469) Pub Date : 2020-01-07 Shigeki Wada; Yuko Omori; Saki Yamashita; Yasuhito Hayashi; Takeo Hama; Yasuhisa Adachi
Dissolved organic matter (DOM) can be partially converted into particulate organic matter via aggregation. Although surface coagulation by bubbles is known to be an aggregation process, a few studies have tested its efficacy for aggregating natural DOM. In the research described here, we tested surface coagulation by bubbles using natural seawater collected from different locations, and achieved organic
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Evaluation of satellite-derived tidal constituents in the South China Sea by adopting the most suitable geophysical correction models J. Oceanogr. (IF 1.469) Pub Date : 2020-01-07 Yanguang Fu; Dongxu Zhou; Xinghua Zhou; Yanfei Sun; Feng Li; Weikang Sun
The focus of this study was first to determine the most suitable geophysical correction models for obtaining satellite-derived sea level height time series in the South China Sea (SCS; 0–26° N, 99° E–121 °E). Analysis of difference of the sea level anomaly standard deviation was conducted to assess the quality of the various correction models. The set of correction models was used to establish the
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The amplification mechanism of a meteo-tsunami originating off the western coast of Kyushu Island of Japan in the winter of 2010 J. Oceanogr. (IF 1.469) Pub Date : 2019-12-06 Katsutoshi Fukuzawa; Toshiyuki Hibiya
A meteo-tsunami is a tsunami-like phenomenon excited by a traveling atmospheric disturbance. In Japan, meteo-tsunamis are frequently observed along the western coast of Kyushu Island during winter–spring. One of the largest meteo-tsunamis occurred on March 3, 2010, where the maximum amplitude of water level oscillations exceeded 1 m in various bays on the western coast of Kyushu Island including Nagasaki
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Comments regarding “Dependence of wind stress across an air–sea interface on wave states” by D. Zhao, M. Li J. Oceanogr. (IF 1.469) Pub Date : 2019-11-13 Dag Myrhaug
A paper by Zhao and Li that was recently published in this journal (J Oceanogr 75:207–223, 2019) presented the dependence of wind stress across an air–sea interface on wave states. The purpose of these comments is to demonstrate that the sea surface roughness formula proposed by Zhao and Li can also be applied to estimate the sea surface roughness based on wind and wave statistics. The average statistical
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Spatiotemporal changes of ocean carbon species in the western North Pacific using parameterization technique J. Oceanogr. (IF 1.469) Pub Date : 2019-11-11 Yutaka W. Watanabe; Bofeng F. Li; Royce Yamasaki; Shun Yunoki; Keiri Imai; Shigeki Hosoda; Yoshiyuku Nakano
We constructed parameterizations for the estimation of dissolved inorganic carbon (DIC) and pH in the western North Pacific, including Japanese coastal regions. Parameterizations, determined as a function of potential temperature (θ) and dissolved oxygen (DO), provided strong correlations with direct measurements for DIC [the coefficient of determination (R2) = 0.99; the root mean square error (RMSE) = 8
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Non-traditional stable isotope geochemistry of marine ferromanganese crusts and nodules J. Oceanogr. (IF 1.469) Pub Date : 2019-11-09 Yazhou Fu
Marine ferromanganese crusts and nodules, which contain a variety of metals, are potential seabed mineral resources. Given their low growth rates, they are regarded as condensed stratigraphic sections that archive millions of years of paleoceanographic information. Ferromanganese crusts and nodules incorporate trace elements like Cu, Zn, Mo, Tl and Ni during growth. The non-traditional isotopic systems
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Marked coastal warming off Tokai attributable to Kuroshio large meander J. Oceanogr. (IF 1.469) Pub Date : 2019-10-29 Shusaku Sugimoto; Bo Qiu; Atsushi Kojima
The Kuroshio takes a large meander (LM) path since summer of 2017 for the first time since the 2004–2005 event and is the sixth LM event since 1965. It has been commonly recognized that a cool water pool is distributed broadly in the inshore region between the Kuroshio and southern coast of the Tokai district, Japan, during the LM periods. By using the recently-developed 1-km high-resolution sea surface
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Temperature and salinity variability at intermediate depths in the western equatorial Pacific revealed by TRITON buoy data J. Oceanogr. (IF 1.469) Pub Date : 2019-10-24 Yuji Kashino; Takuya Hasegawa; Fadli Syamsudin; Iwao Ueki
We investigated ocean variability at intermediate depths (300–750 m) in the western equatorial Pacific (WEP) using data from underwater sensors of the Triangle Trans-Ocean Buoy Network (TRITON) buoys. The data were specially processed because high accuracy is necessary for such an application, and we confirmed that sufficient accuracy was achieved. Variability of the temperature and salinity was large
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Experimental measurements of the sinking speed of sperm of an acroporid coral, Acropora tenuis, in static seawater J. Oceanogr. (IF 1.469) Pub Date : 2019-10-21 Tokihiro Kono; Ryota Nakamura; Makoto Omori
The dispersion of Acropora coral sperm is critical for sexual reproduction via external fertilization. Sperm sinking likely plays an important role in the process of dispersion, but its rate of sinking is still unclear. To estimate the sinking speed of coral sperm without turbulence, two experiments were conducted in a water tank filled with 500 L of static seawater in the 0–60 cm layer. In Exp. 1
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Phytoplankton pigments and community structure in the northeastern tropical pacific using HPLC-CHEMTAX analysis J. Oceanogr. (IF 1.469) Pub Date : 2019-10-18 Cristina Miranda-Alvarez; Adriana González-Silvera; Eduardo Santamaría-del-Angel; Jorge López-Calderón; Victor M. Godínez; Laura Sánchez-Velasco; Rafael Hernández-Walls
This study investigated the relationship between phytoplankton biomass and taxonomic composition and hydrographic variables in the Northeastern Tropical Pacific for June 2015, March 2016, and September 2016. Hydrographic data were measured between surface and 100 m; samples were collected at the surface and the deep chlorophyll maximum (DCM) along one or two transects. Pigments were quantified by high-performance
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