マスナガ エイジ
増永 英治講師
Eiji Masunaga

■研究者基本情報

組織

  • 地球・地域環境共創機構
  • 工学部 都市システム工学科
  • 理工学研究科(博士前期課程) 都市システム工学専攻
  • 理工学研究科(博士後期課程) 社会インフラシステム科学専攻
  • 応用理工学野 都市システム工学領域

研究分野

  • 社会基盤(土木・建築・防災), 水工学, 海岸環境工学
  • 環境・農学, 環境動態解析, 環境動態解析
  • 自然科学一般, 大気水圏科学, 気象・海洋物理・陸水学

研究キーワード

  • 海洋数値モデル
  • 非線形内部波
  • 乱流混合
  • 沿岸海洋物理学

学位

  • 2015年03月 博士(海洋科学)(東京海洋大学)
  • 2012年03月 修士(海洋科学)(東京海洋大学)

学歴

  • 2015年03月, 東京海洋大学, 大学院海洋科学技術研究科, 応用環境システム学専攻

経歴

  • 2022年06月 - 2023年03月, Scripps Institute of Oceanography, University of California San Diego, Visiting research scholar
  • 2015年08月 - 2016年03月, 東京海洋大学, 海洋科学部, 博士研究員
  • 2015年04月 - 2015年08月, Stanford University, Civil and Environmental Engineering Department, 客員研究員
  • 2012年04月 - 2015年03月, 東京海洋大学, 海洋科学部, リサーチアシスタント

委員歴

  • 2023年04月 - 現在, 常陸河川国道事務所 総合評価審査分科会, 国土交通省
  • 2020年10月 - 現在, Section Secretary (Ocean Science Section), Asia Oceania Geosciences Society
  • 2020年10月 - 現在, 北浦水質改善計画検討会 委員, 国土交通省
  • 2019年04月 - 現在, 論文編集委員会, 沿岸域学会

■研究活動情報

受賞

  • 2022年09月, 日本海洋学会賞・岡田賞, 沿岸域における混合過程と水理環境に関する研究
    国内学会・会議・シンポジウム等の賞
  • 2021年01月, 三陸海域研究論文知事表彰(岩手県知事賞), 三陸沿岸域で発生する内部潮汐や関連する混合現象に関わる研究
    その他の賞
  • 2019年06月, 第3回めぶきビジネスアワード 大学発イノベーション賞, 高精度海洋数値モデルと機械学習システムを用いた沿岸海域海況予測システムの提供, めぶきフィナンシャルグループ
    増永英治
    出版社・新聞社・財団等の賞
  • 2018年10月, Best Presentation Award (Oral), Mixing processes associated with hypoxia in Lake Kasumigaura, 17th World Lake Conference
    Eiji Masunaga
    国際学会・会議・シンポジウム等の賞
  • 2017年05月, 日本海洋学会奨励論文賞, 日本海洋学会
    学会誌・学術雑誌による顕彰

論文

  • Turbulent mixing layers and associated diffusive fluxes across the epilimnion and metalimnion in stratified large Lake Biwa
    Hikaru Homma; Eiji Masunaga; Ilia Ostrovsky; Hidekatsu Yamazaki, Abstract

    Stratification and turbulent mixing have an immense impact on biogeochemical regimes and ecosystem dynamics in stratified large lakes. This study investigates the physical properties of the epi‐ and metalimnion of Lake Biwa (Japan), focusing on the persistent vertical diffusive fluxes due to turbulent mixing in the lower metalimnion and their effects on upward nitrate transport. We conducted 24‐h observations at an offshore station in the summer for three consecutive years to examine the temporal and vertical variations of stratification and turbulence. A mooring system provided long‐term data on stratification and current velocity, while thermal profiles along two offshore transects were collected to investigate lateral changes. Our findings revealed strong stratification in the upper metalimnion, where vertical diffusive fluxes were essentially suppressed. Distinct turbulent mixing layers were identified near the water surface and within the moderately stratified lower metalimnion. Field data and numerical model suggested that the turbulence in the lower metalimnion was driven by shear instability, straining, and/or wave–wave interactions linked with the persistent internal waves that occur even during weak winds. Vertical eddy diffusivity of > 10−5 m2 s−1 in the lower metalimnion was associated with rather strong turbulence, which has not been reported in other large lakes. The elevated turbulence resulted in an upward nitrate flux of 0.2 mmol N m−2 d−1 across the lower metalimnion, indicating that the upward nutrient transport could support primary productivity and play an important ecological role in deep stratified lakes., Wiley
    Limnology and Oceanography, 2025年, [査読有り]
  • Eddy-covariance measurements of turbulent fluxes across the oxygen-depleted benthic layer in a shallow stratified lake
    Yusuke Kawaguchi; Eiji Masunaga; Takao Ouchi; Tatsumi Kitamura; Eun Yae So
    Limnology, 2025年01月, [査読有り]
  • 遠州灘沿岸域における黒潮流路変動に伴う栄養塩輸送および表層一次生産の変 動特性について               
    鯰江 岳; 内山雄介; 張 旭; 増永英治
    土木学会論文集B2(海岸工学), 2024年11月, [査読有り]
  • 海岸地形に影響される浅水域における吹送流モニタリングと数値計算を用いた再現検証               
    吉田 壮汰; 増永 英治; 北村 立実; 大内 孝雄, 責任著者
    土木学会論文集(B2海岸工学), 2024年11月, [査読有り]
  • 領域海洋モデル全域から放流した粒子追跡実験を用いた東日本南岸海域の物質輸送過程の評価               
    佐近 淳平; 増永 英治; 内山 雄介, 責任著者
    土木学会論文集(B2海岸工学), 2024年11月, [査読有り]
  • 〔主要な業績〕Shoaling internal tides propagating from a shallow ridge modulated by the Kuroshio
    Eiji Masuanga; Hitoshi Tamura; Yusuke Uchiyama, 筆頭著者
    Journal of Geophysical Research: Oceans, 2024年08月, [査読有り]
  • 〔主要な業績〕Numerical simulations of internal tide dynamics in a steep submarine canyon
    Eiji Masunaga; Matthew H. Alford; Andrew J. Lucas; Andrea Rodriguez-Marin Freudmannb, 筆頭著者, American Meteorological Society
    Journal of Physical Oceanography, 2023年11月, [査読有り]
  • 粒子追跡モデルとドリフターデータを用いた日本海における物質輸送過程の研究               
    原田 一宏,増永 英治,内山 雄介, 責任著者, 土木学会
    土木学会論文集(B2海岸工学), 2023年11月, [査読有り]
  • 傾圧と順圧的運動に関連する東京湾における運動エネルギーの評価               
    渡邉 暦,到津 春樹,増永 英治, 責任著者, 土木学会
    土木学会論文集(B2海岸工学), 2023年11月, [査読有り]
  • 沖合から伝播する内部潮汐の砕波による河川水の混合に関する研究               
    門馬 宏典,増永 英治, 責任著者, 土木学会
    土木学会論文集(B2海岸工学), 2023年11月, [査読有り]
  • 夏季の気象変化による成層の発達が及ぼす霞ヶ浦への影響の評価               
    松本 大樹,増永 英治,横木 裕宗, 責任著者, 土木学会
    土木学会論文集(G環境), 2023年09月, [査読有り]
  • 北浦の貧酸素水塊形成に係る底層水および底泥の酸素消費の影響評価               
    北村 立実,増永 英治,鮎川和 泰,大内 孝雄,湯澤 美由紀,佐藤 和貴,清家 泰,福島 武彦, 水環境学会
    水環境学会誌, 2023年07月, [査読有り]
  • 〔主要な業績〕Vertical mixing and oxygen flux caused by daily sea breezes in a shallow stratified lake
    Eiji Masunaga; Sachihiko Itoh; Tatsumi Kitamura, 筆頭著者
    Limnology, 2023年04月, [査読有り]
  • 沿岸域における混合過程と水理環境に関する研究:,内部潮汐と混合現象
    増永英治, 筆頭著者, 日本海洋学会
    海の研究(Oceanography in Japan), 2023年03月, [査読有り], [招待有り]
  • ASSESSMENT OF THE IMPACT OF STRATIFICATION DEVELOPMENT BY CLIMATE CHANGE DURING THE SUMMER SEASON IN LAKE KASUMIGAURA
    Daiki MATSUMOTO; Eiji MASUNAGA; Hiromune YOKOKI, Japan Society of Civil Engineers
    Japanese Journal of JSCE, 2023年
  • 領域海洋モデルを用いた洋上風力発電施設の適地選定システム開発に関する基礎的研究               
    玉井 駿壮・内山 雄介・Xu Zhang・増永 英治・辻 一洋・山崎 秀勝
    土木学会論文集(B2海岸工学), 2022年11月, [査読有り]
  • 複数定点観測データを用いた東京湾における水平物理構造と混合状態の評価               
    到津 春樹・増永 英治, ラスト(シニア)オーサー
    土木学会論文集(B2海岸工学), 2022年11月, [査読有り]
  • 沿岸地形が影響する風応力による鉛直混合の観測と評価               
    佐藤 和貴・増永 英治・北村 立実, 責任著者
    土木学会論文集(B2海岸工学), 2022年11月, [査読有り]
  • 定常流,振動流及び密度成層を考慮した海洋構造物周辺の数値実験               
    山﨑 彩花・増永 英治・内山 雄介・辻 一洋・山崎 秀勝, 責任著者
    土木学会論文集(B1水工学), 2022年09月, [査読有り]
  • Seasonal variability of upper ocean primary production along the Kuroshio off Japan: Roles of eddy-driven nutrient transport
    Xu Zhang; Yusuke Uchiyama; Eiji Masunaga; Yota Suzue and Hidekatsu Yamazaki, We assessed spatial and seasonal variabilities of eddy-driven vertical nutrient fluxes, which are essential for maintaining primary production in the upper ocean. A climatological model based on a Regional Oceanic Modeling System (Regional Oceanic Modeling System) coupled with a Nutrient Phytoplankton Zooplankton and Detritus (NPZD) biogeochemical model at a submesoscale eddy-permitting resolution was used to investigate the mechanisms driving such variabilities around the Kuroshio, off the coast of Japan. The model realistically reproduced the spatial segmentations in primary production on both sides of the Kuroshio path with a higher chlorophyll-a concentration on the northern side than the southern side. In winter, downward eddy-induced nitrate flux is predominantly provoked in the upstream Kuroshio region (KR), while upward nitrate fluxes prevail in the downstream Kuroshio Extension (KE) region, due to both shear and baroclinic instabilities. Baroclinic instability plays a crucial role in inducing seasonal variability, leading to enhancement (reduction) of the eddy flux in winter (summer), particularly in regions away from the Kuroshio axis. Furthermore, we found that the influence of the Izu-Ogasawara Ridge, located in the KR, on regional dynamics and resultant spatial variability of the biogeochemical response are mostly confined in the KR. The Kuroshio is less turbulent in the upstream of the ridge, while it becomes unstable to shed mesoscale eddies in laterally wider and vertically deeper regions downstream. Consequently, although the near-surface nitrate concentration is lower downstream, the upward eddy-driven nitrate flux is more effective in maintaining active primary production due to the shear and baroclinic instabilities in winter., Frontiers Media SA
    Frontiers in Marine Science, 2022年08月, [査読有り]
  • Seasonal cycle of the confluence of the Tsugaru Warm, Oyashio, and Kuroshio currents east of Japan
    S. Itoh; E. Tsutsumi; E. Masunaga; T. T. Sakamoto; K. Ishikawa; D. Yanagimoto; Y.; Hoshiba; H. Kaneko; D. Hasegawa; K. Tanaka; H. Fukuda and T. Nagata, American Geophysical Union (AGU)
    Journal of Geophysical Research: Oceans, 2022年08月, [査読有り]
  • 〔主要な業績〕Modulation of submesoscale motions due to tides and a shallow ridge along the Kuroshio
    Eiji Masunaga; Yusuke Uchiyama; Xu Zhang; Waku Kimura and Taichi Kosako, 筆頭著者, This study investigated submesoscale motions (SMs) and transport over the Izu-Ogasawara Ridge, located off mainland Japan, using a double-nested Regional Oceanic Modeling System (ROMS). Both the Kuroshio and tides largely influence physical processes in this area. The mean and submesoscale kinetic energies (MKE and SKE, respectively) were calculated using a horizontal Gaussian filter. Tidal forcing enhances SKE through Reynolds stress due to mean velocity shear (barotropic conversion); meanwhile, tides suppress the MKE and total kinetic energy. This implies that tidal forcing contributes to energy transfer from large-scale motions to smaller scales, which results in accelerated kinetic energy dissipation. Energy conversion from submesoscale potential energy to SKE (baroclinic conversion) is reduced by tidal forcing. In the summer, SKE is generated by barotropic conversion and suppressed by negative baroclinic conversion. On the other hand, in winter, SKE is enhanced by both barotropic and baroclinic conversions.
    Deep Sea Research: Part I, 2022年08月, [査読有り]
  • 自動昇降装置を用いた夏季における北浦の水温成層と貧酸素水塊の形成・消失およびリン溶出過程の検討               
    北村 立実; 鮎川 和泰; 増永 英治; 小室 俊輔; 大内 孝雄; 湯澤 美由紀; 浅岡 大輝; 三上 育英; 清家 泰; 福島 武彦
    水環境学会誌, 2022年06月
  • 〔主要な業績〕Variability of the diapycnal mixing coefficient in coastal oceans investigated with direct,microstructure measurements
    Eiji Masunaga; Subhas K. Venayagamoorthy; Koyo Wada; Hidekatsu Yamazaki, 筆頭著者
    Journal of Marine Systems, 2022年03月, [査読有り]
  • DEVELOPMENT OF AN EVALUATION SYSTEM FOR SUITABILITY OF OFFSHORE WIND FARM SITES AROUND JAPAN BASED ON A REGIONAL OCEAN CIRCULATION–BIOGEOCHEMICAL MODEL
    Toshitake TAMAI; Yusuke UCHIYAMA; Xu ZHANG; Eiji MASUNAGA; Kazuhiro TSUJI; Hidekatsu YAMAZAKI, Japan Society of Civil Engineers
    Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 2022年
  • 粒子追跡モデルを用いた相模湾及び駿河湾周辺の物質輸送過程の解析               
    井上孝義・増永英治・小硲大地・Xu Xhang・内山雄介, 責任著者
    土木学会論文集(B2海岸工学), 2021年11月, [査読有り]
  • 東京湾湾奥部における貧酸素水塊に関わる物理構造と混合状態               
    到津春樹・増永英治, ラスト(シニア)オーサー
    土木学会論文集(B2海岸工学), 2021年11月, [査読有り]
  • 領域海洋モデルを用いた黒潮・親潮混合水域における水塊分布に関する研究               
    池田雅・増永英治・鈴江洋太・伊藤幸彦・内山雄介, 責任著者
    土木学会論文集(B2海岸工学), 2021年11月, [査読有り]
  • 北浦における貧酸素水塊の詳細分布と貧酸素水域面積の推計               
    小室俊輔,北村立実,大内孝雄,増永英治,浅岡大輝,鮎川和泰,三上育英,清家泰,湯澤美由紀,福島武彦, 水環境学会
    水環境学会誌, 2021年09月, [査読有り]
  • Diel vertical migration promotes zooplankton horizontal patchiness               
    Bingzhang Chen; Eiji Masunaga; S. Lan Smith; Hidekatsu Yamazaki
    Journal of Oceanography, 2021年02月, [査読有り]
  • 粒子追跡モデルを用いた黒潮から沿岸域への物質輸送過程の評価
    増永 英治; 木村 和久; 小硲 大地; 張 旭; 内山 雄介, 筆頭著者
    土木学会論文集(B2海岸工学), 2020年11月, [査読有り]
  • 地形と成層の変化に関連する風応力による混合応答時間の評価               
    浅岡 大輝; 増永 英治; 小室 俊輔; 北村 立実, 責任著者
    土木学会論文集(B2海岸工学), 2020年11月, [査読有り]
  • 〔主要な業績〕Baroclinic Residual Circulation and Mass Transport Due to Internal Tides
    Eiji Masunaga; Robert S. Arthur; Hidekatsu Yamazaki, 筆頭著者
    Journal of Geophysical Research: Oceans, 2020年04月, [査読有り]
  • 〔主要な業績〕Stratification and mixing processes associated with hypoxia in a shallow lake (Lake Kasumigaura, Japan)               
    Eiji Masunaga; Shunsuke Komuro, 筆頭著者
    Limnology, 2020年04月, [査読有り]
  • 粒子追跡モデルを用いた黒潮から沿岸域への物質輸送過程の評価
    増永 英治; 木村 和久; 小硲 大地; 張 旭; 内山 雄介, Japan Society of Civil Engineers
    土木学会論文集B2(海岸工学), 2020年, [査読有り]
  • 沿岸地形と風応力が形成する複雑な密度構造と混合状態の高精度計測               
    増永英治,浅岡 大輝,小室 俊輔,松本 俊一,小野 正人,番場 泰彰, 筆頭著者
    土木学会論文集B2(海岸工学), 2019年11月, [査読有り]
  • Lagrange粒子追跡モデルを用いた伊豆諸島周辺海域の物質輸送及び拡散の評価
    木村和久,増永英治,小硲大地,内山雄介, 責任著者
    土木学会論文集B2(海岸工学), 2019年11月, [査読有り]
  • TRANSPORT PROCESSES AROUND THE IZU-CHAIN ISLANDS INVESTIGATED WITH A LAGRANGIAN PARTICLE TRACKING MODEL
    Waku KIMURA; Eiji MASUNAGA; Taichi KOSAKO; Yusuke UCHIYAMA, Japan Society of Civil Engineers
    Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 2019年, [査読有り]
  • Observation of three dimensional flow structures and effluent transport around fish cages using a towed ADCCP and free-fall multi-parameter profiler
    Hidekatsu Yamazaki; Wataru Aoyama; Eiji Masunaga; Mamoru Tanaka
    Aquaculture Research, 2019年, [査読有り]
  • 〔主要な業績〕Strong internal waves generated by the interaction of the kuroshio and tides over a shallow ridge
    Eiji Masunaga; Yusuke Uchiyama; Hidekatsu Yamazaki, © 2019 American Meteorological Society. The Kuroshio and tides significantly influence the oceanic environment off the Japanese mainland and promote mass/heat transport. However, the interaction between the Kuroshio and tides/internal waves has not been examined in previous works. To investigate this phenomenon, the two-dimensional high-resolution nonhydrostatic oceanic Stanford Unstructured Nonhydrostatic Terrain-Following Adaptive Navier–Stokes Simulator (SUNTANS) model was employed. The results show that strong internal tides propagating upstream in the Kuroshio are generated at a near-critical internal Froude number (Fri = 0.91). The upstream internal wave energy flux reaches a magnitude of 12 kW m-1, which is approximately 3 times higher than that of internal waves without the Kuroshio. On the other hand, under supercritical conditions, the Kuroshio suppresses the internal wave energy flux. The interaction of internal tides and the Kuroshio also generates upstream propagating high-frequency internal waves and solitary wave packets. The high-frequency internal waves contribute to the increase in the total internal wave energy flux up to 40% at the near-critical Fri value. The results of this study suggest that the interaction of internal tides and the Kuroshio enhances the upstream propagating internal tides under the specified conditions (Fri ~ 1), which may lead to deep ocean mixing and transport at significant distances from the internal wave generation sites.
    Journal of Physical Oceanography, 2019年, [査読有り]
  • Mixing processes associated with hypoxia in Lake Kasumigaura               
    Eiji Masunaga; Tomoko Ozawa, 筆頭著者
    7th World Lake Conference proceedings, 2018年10月, [査読有り]
  • 〔主要な業績〕Dynamics of Internal Tides Over a Shallow Ridge Investigated With a High-Resolution Downscaling Regional Ocean Model
    Eiji Masunaga; Yusuke Uchiyama; Yota Suzue; Hidekatsu Yamazaki, ©2018. American Geophysical Union. All Rights Reserved. This study investigates the dynamics of tidally induced internal waves over a shallow ridge, the Izu-Ogasawara Ridge off the Japanese mainland, using a downscaled high-resolution regional ocean numerical model. Both the Kuroshio and tides contribute to the field of currents in the study area. The model results show strong internal tidal energy fluxes over the ridge, exceeding 3.5 kW m−1, which are higher than the fluxes along the Japanese mainland. The flux in the upstream side of the Kuroshio is enhanced by an interaction of internal waves and currents. The tidal forcing induces 92% of the total internal wave energy flux, exhibiting the considerable dominance of tides in internal waves. The tidal forcing enhances the kinetic energy, particularly in the northern area of the ridge where the Kuroshio Current is not a direct influence. The tidal forcing contributes to roughly 30% of the total kinetic energy in the study area.
    Geophysical Research Letters, 2018年04月, [査読有り]
  • A three-dimensional numerical study of river plume mixing processes in Otsuchi Bay, Japan               
    Sasmal, K; Masunaga, E; Webb, A; Fringer, O. B; Gross, E. S; Rayson, M. D; Yamazaki, H
    Journal of Oceanography, 2018年, [査読有り]
  • Impacts of two super typhoons on the Kuroshio and marginal seas off the Pacific coast of Japan
    HIroaki Tada; Yusuke Uchiyama; Eiji Masunaga, © 2017 Elsevier Ltd High-resolution downscaling ocean modeling was conducted to investigate the impacts of two super typhoons on the Kuroshio in the fall of 2014 off the Kyushu and Shikoku Islands, Japan. The model result was compared with field observations and satellite altimetry. The synoptic and mesoscale oceanic structures around the Kuroshio exhibit a good reproducibility. The typhoons generated near-inertial oscillations (NIOs) and near-inertial internal waves (NIIWs) around the Kuroshio path, particularly on the right side of the typhoon tracks. The NIOs developed in the mixed layer to alter the direction of the Kuroshio by ~30°. The associated velocity off the Shikoku and Kyushu Islands was significantly decelerated by ~0.2 ms−1. The velocity almost vanished off Kyushu Island and thus induced an unstable fluctuating path shortly after both typhoons passed over that region. The NIIWs were also excited at the thermocline, resulting in the oscillation of the Kuroshio path occurred in the entire water column. In contrast, off Shikoku Island, the typhoons shifted the Kuroshio path northward to enhance the interactions with the topographies. This shift caused considerable eddy shedding from the capes that resulted in mesoscale counterclockwise circulations as cyclonic quasi-standing eddies with a shedding period of ~3 days in the north of the Kuroshio path. The magnitude, direction, and meridional location of the path of the Kuroshio prominently fluctuated with the propagation of these eddies, manifested off Shikoku Island. Furthermore, these eddies induced sporadic northward intrusions of the Kuroshio warm water through the Kii Channel into the Seto Inland Sea (SIS), where a weak but persisting southward outflow prevails under normal conditions. Therefore, the process could collectively be called the “typhoon-Kuroshio-eddy interaction” which conceptually differs from the “typhoon-eddy-Kuroshio interaction” in the previous studies, where the Kuroshio was modulated by eddy collision. The wind stress curl and intrusions associated with the typhoons jointly provoked the inversion of the counterclockwise SIS residual circulation. The resultant spatially averaged volume flux was ~8 times as high as that under normal conditions.
    Deep-Sea Res. Part I, 2018年, [査読有り]
  • 複数気候モデルによる海面上昇に伴う浸水影響の不確実性評価               
    土田 晃次郎,田村 誠,熊野 直子,増永 英治,横木 裕宗
    土木学会論文集G(環境), 2018年, [査読有り]
  • 高解像度数値計算技術を用いた東京湾湾奥の物理構造の解明               
    増永英治,木村和久,鯉渕幸夫, 筆頭著者
    土木学会論文集B2(海岸工学), 2018年, [査読有り]
  • 珊瑚環礁内における流動構造と物質輸送過程の解明               
    小池海,増永英治,横木裕宗, 責任著者
    土木学会論文集B2(海岸工学), 2018年, [査読有り]
  • 内部潮汐を考慮した伊豆大島周辺海域における潮流予測システムの開発と運用               
    増永英治,山崎秀勝,山口邦久, 筆頭著者
    土木学会論文集B2(海岸工学), 2018年, [査読有り]
  • 〔主要な業績〕Dynamics and Energetics of Trapped Diurnal Internal Kelvin Waves around a Midlatitude Island
    Eiji Masunaga; Oliver B. Fringer; Yujiro Kitade; Hidekatsu Yamazaki; Scott M. Gallager, The generation of trapped and radiating internal tides around Izu-Oshima Island located off Sagami Bay, Japan, is investigated using the three-dimensional Stanford Unstructured Nonhydrostatic Terrain-following Adaptive Navier-Stokes Simulator (SUNTANS) that is validated with observations of isotherm displacements in shallow water. The model is forced by barotropic tides, which generate strong baroclinic internal tides in the study region. Model results showed that when diurnal K-1 barotropic tides dominate, resonance of a trapped internal Kelvin wave leads to large-amplitude internal tides in shallow waters on the coast. This resonance produces diurnal motions that are much stronger than the semidiurnal motions. The weaker, freely propagating, semidiurnal internal tides are generated on the western side of the island, where the M-2 internal tide beam angle matches the topographic slope. The internal wave energy flux due to the diurnal internal tides is much higher than that of the semidiurnal tides in the study region. Although the diurnal internal tide energy is trapped, this study shows that steepening of the Kelvin waves produces high-frequency internal tides that radiate from the island, thus acting as a mechanism to extract energy from the diurnal motions., AMER METEOROLOGICAL SOC
    JOURNAL OF PHYSICAL OCEANOGRAPHY, 2017年10月, [査読有り]
  • 〔主要な業績〕Sediment resuspension and the generation of intermediate nepheloid layers by shoaling internal bores               
    Eiji Masunaga; Robert S. Arthur; Oliver B. Fringer; Hidekatsu Yamazaki, 筆頭著者
    Journal of Marine Systems, 2017年02月, [査読有り]
  • 日本における海面上昇への適応を目的とした防護費用の将来推計
    熊野直子,土田光次郎,田村誠,増永英治,桑原祐史,横木裕宗, 気候変動に伴う海面上昇への適応策を講じるに当たっては,複数の対策の費用便益を考慮した効率的な選択が重要である.その際に,海岸防護の費用を把握することは適応策を判断するための有用な情報となる.そこで本稿では,まず,これまで設置された防護施設(堤防・護岸)費用を収集し,一人当たり実質GDPとの関係やモデル堤防を用いて防護新設・嵩上げの将来費用を導出した.次に,日本において将来の海面上昇や社会経済を考慮し,堤防の新設と嵩上げを組み合わせた防護シナリオに基づく将来の防護費用の評価を行った.これらの防護費用を過去の実質GDPと海岸事業費の割合と比較した.その結果,現在設置済みの施設の更新は新設することでも可能だが,新規設置と嵩上げの両方を組み合わせることで費用はさらに抑えられることが確認できた., 公益社団法人 土木学会
    土木学会論文集B3(海洋開発), 2017年, [査読有り]
  • RCP・SSPシナリオに基づく全球沿岸域での海面上昇による浸水影響評価
    四栗瑞樹,田村 誠,熊野 直子,増永 英治,横木 裕宗, 土木学会
    地球環境シンポジウム論文集, 2017年, [査読有り]
  • 黒潮と内部波が影響する伊豆諸島周辺海域における流動場の解明
    増永英治,鈴江洋太,内山雄介,山崎秀勝, 筆頭著者, 潮汐と内部潮汐が伊豆諸島周辺海域に及ぼす影響を評価するために,潮汐の外力を組み込んだ領域海洋モデルROMSを用いた解析を実施した.内部波のエネルギーフラックスを推定した結果,伊豆諸島周辺では非常に強い内部波が発生していることがわかった.内部波のエネルギ-フラックスは潮汐によってバックグラウンドの値の10倍以上に増幅され,対象海域の内部波は潮汐によって支配されていることがわかった.また,潮汐により運動エネルギー全体量は増大するが,順圧的な運動エネルギーはむしろ減少し,傾圧(内部波)成分の運動エネルギーは増大していた.したがって,対象海域では黒潮や風に比べ潮汐によって発生した傾圧的な流れを伴う内部波が流動場に対して卓越して影響していること,内部潮汐が伊豆諸島周辺海域の海水運動に強く寄与していることがわかった., 土木学会
    土木学会論文集B2(海岸工学), 2017年, [査読有り]
  • Coastal observation systems to monitor physical, chemical, and biological parameters
    Hidekatsu Yamazaki; Eiji Masunaga; Scott Gallager; Mamoru Tanaka; Marika Takeuchi; Kazuo Amakasu; Hayato Kondo, We have developed a free-fall multi-parameter profiler (YODA Profiler) to measure various physical and biological parameters in coastal ocean. We found internal bores create a strong mixing event. Sediment resuspension is associated with the mixing event and also AZFP detected fish school at the front of bore. We have deployed a cable observatory system (Oshima Coastal Environment data Acquisition Network System, OCEANS) in a coastal area to monitor coastal ecosystem continuously. OCEANS can measure various physical, chemical and biological parameters simultaneously, and operates a plankton imaging system (Continuous Plankton Imaging and Classification System, CPICS). Based on acquired images of phytoplankton and zooplankton, we are investigating how planktonic biodiversity is affected by multi-scale physical processes, such as Kuroshio and internal waves. We are developing a technique to predict the biodiversity of plankton from three-dimensional hydrodynamic model using a newly developed plankton ecosystem model. We are also developing a AUV (MEMO-pen) that carries CPICS as well as microstructure profiler (TurboMAP) in order to simultaneously observe turbulence and plankton. We will introduce the most recent results from these observation systems., Acoustical Society of America (ASA)
    Journal of the Acoustical Society of America, 2016年10月01日
  • 〔主要な業績〕Strong turbulent mixing induced by internal bores interacting with internal tide-driven vertically sheared flow
    Eiji Masunaga; Oliver B. Fringer; Hidekatsu Yamazaki; Kazuo Amakasu, We observed the formation of an internal bore interacting with the vertically sheared flow generated during the previous phase of the internal tide, which resulted in strong turbulent mixing. The rate of turbulent kinetic energy dissipation reached on the order of 10(-5)Wkg(-1) during the event. Numerical simulations reproduced the observed interaction of internal bores with the sheared flow and verified the hypothesized breaking and mixing mechanism. The numerical results indicated that the Iribarren number, or the ratio of the topographic slope to the internal wave slope, plays a major role in the mixing intensity and types of internal bores. It was found that waves with low Iribarren numbers lead to bores that interact with vertically sheared flows induced by the previous phase of the internal tide and are more likely to produce strong wave breaking and mixing., AMER GEOPHYSICAL UNION
    GEOPHYSICAL RESEARCH LETTERS, 2016年03月, [査読有り]
  • 〔主要な業績〕An observational and numerical study of river plume dynamics in Otsuchi Bay, Japan
    Eiji Masunaga; Oliver B. Fringer; Hidekatsu Yamazaki, A newly developed tow-yo profiler (YODA Profiler) and a fully nonhydrostatic numerical model, SUNTANS, are used in this study to investigate river plume mixing in Otsuchi Bay, a ria estuary located in Iwate, Japan. Several field campaigns were conducted in the bay during early summer, late summer, and late winter. The YODA Profiler reveals fine features related to a shallow river plume that experiences rapid mixing events during the summer campaigns with a time scale of O(1) hour. These events coincide with strong baroclinic currents and large fluctuations in thermocline and pycnocline depths related to shoaling internal tides. The combined effects of wind stress and baroclinic flow appear to generate a strong shear near the surface layer and enhance mixing of the river plume, with typical eddy diffusivity values of O(10(-4)) m(2) s(-1). To investigate the physical mechanisms involved, numerical simulations are conducted with tidal and wind forcing. Analysis of tidal forcing mechanisms reveals that mixing near the river mouth (and upstream) is dominated by the barotropic tide, while turbulent mixing in the middle of the bay is significantly enhanced by the baroclinic internal tide. Wind forcing is also important for river plume dynamics; along-channel wind forcing mixes the river plume and transports it horizontally. Overall, this study suggests that all three forcing mechanisms (barotropic tide, baroclinic tide, and wind) are important for mixing processes of the river plume in Otsuchi Bay., SPRINGER
    JOURNAL OF OCEANOGRAPHY, 2016年02月
  • 沿岸域におけるプランクトン生態のモニタリング手法の開発               
    山崎秀勝; 増永英治; H. Foloni-Neto; S. Gallager
    沿岸海洋研究, 2016年01月, [査読有り]
  • 〔主要な業績〕Mixing and sediment resuspension associated with internal bores in a shallow bay               
    Masunaga, E; H. Homma; H. Yamazaki; O. Fringer; T. Nagai; Y. Kitade; A. Okayasu, 筆頭著者
    Continental Shelf Research, 2015年09月, [査読有り]
  • 〔主要な業績〕A new tow-yo instrument to observe high-resolution coastal phenomena
    Eiji Masunaga; Hidekatsu Yamazaki, Field observations in coastal and estuarine regions are important for studying physical and biological features. Recent studies have presented fine-scale physical features from numerical models and acoustic surveys. However, high spatial resolution data of physical structures are difficult to obtain, since the conventional CTD survey requires a stop-and-measure ship operation. To solve this issue, we have developed a new, portable tow-yo instrument, Yoing Ocean Data Acquisition Profiler (YODA Profiler), that continuously observes many vertical profiles of the fine-scale features in coastal regions. Using the YODA Profiler, we were able to rapidly obtain high-resolution data in a shallow estuary. The results showed fine-scale complicated internal wave features, upslope propagating fronts and a patchy distribution of phytoplankton. These observations are consistent with recent numerical models and acoustic surveys, as well as with the critical angle theory for internal wave reflections along a bottom slope. We have also developed a statistical technique to estimate the rate of turbulent kinetic energy dissipation, e, from the variance of dC/dz data. Using this technique we were able to estimate the turbulent kinetic energy dissipation rate associated with river outflow and internal waves in the river mouth. (C) 2013 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
    JOURNAL OF MARINE SYSTEMS, 2014年01月, [査読有り]
  • Resuspension and lateral dispersal of sediments due to shoaling internal waves               
    Masunaga, E; H. Yamazaki; T. Nagai; O; Fringer, 筆頭著者
    IMBER newsletter, 2013年12月, [査読有り]
  • TEST               

MISC

  • Internal Wave Breaking Dynamics and Associated Mixing in the Coastal Ocean, Encyclopedia of Ocean Science, Third Edition
    Eiji Masunaga; Robert S. Arthur; Oliver B. Fringer
    Encyclopedia of Ocean Science, 3rd Edition, 2019年, [査読有り], [招待有り]
    筆頭著者

講演・口頭発表等

  • Horizontal diffusion and resident time scale evaluated by a tracer dispersion model for Lake Kasumigaura               
    Eiji Masunaga; Oliver B. Fringer
    JpGU Meeting 2024, 2024年05月
  • Observations of vertical mixing structures in La Jolla Canyon off South California               
    Eiji Masunaga; Matthew H. Alford
    Ocean Science Meeting 2024, 2024年02月
  • 沿岸地形にトラップされた内部潮汐が引き起こす擬似的な M2順圧潮汐流(Quasi Barotropic Tides)               
    増永 英治; Kevin Okun; Geno Pawlak
    日本海洋学会 2023年度秋季大会, 2023年09月
  • Dynamics of Internal Tides Generated by a Flow-tide Interaction Along the Kuroshio               
    Eiji MASUNAGA; Hitoshi TAMURA; Yusuke UCHIYAMA
    AOGS Meeting 2023, 2023年08月
  • Internal tide dynamics and energy dissipation in La Jolla Canyon               
    Eiji Masunaga; Matthew; H. Alford; Drew J. Lucas; Andrea RMF
    JpGU Meeting 2023, 2023年05月
  • 岡田賞受賞記念講演               
    増永英治
    2022年度日本海洋学会秋季大会, 2022年09月, [招待有り]
  • Observations of vertical mixing and associated transport in a shallow lake, Lake Kasumigaura, Japan               
    Eiji Masunaga; Tastumi Kitamura; Sachihiko Itoh
    JpGU Meeting 2022, 2022年05月, [招待有り]
  • Circulation and water exchange in shallow lakes influenced by wind-induced mixing               
    Eiji Masunaga Tatsumi Kitamura
    JpGU Meeting 2022, 2022年05月
  • 黒潮と潮汐が影響する伊豆小笠原海嶺北部における サブメソスケール渦と物質輸送               
    増永英治,内山雄介,Xu Zhang,木村和久,小硲大地
    2021年度日本海洋学会秋季大会, 2021年09月, 日本海洋学会
  • Submeso-scale Eddies Generated in the Vicinity of the Izu-Ogasawara Ridge Investigated with aRegional Oceanic Simulator               
    Eiji Masunaga; Xu Zhang; Yusuke Uchiyama
    AOGS Meeting 2021, 2021年08月
  • Vertical mixing and mass transport in a shallow lake, Lake Kasumigaura, Japan               
    Eiji Masunaga; Tatsumi Kitamura; Sachihiko Itoh
    JpGU Meeting 2021, 2021年06月, JpGU
  • 黒潮が影響する伊豆小笠原海嶺北部における               
    増永 英治・内山 雄介・張 旭
    日本海洋学会2020年度秋季大会, 2020年11月26日
  • 霞ヶ浦での乱流混合過程について               
    増永英治
    海洋乱流に関する観測およびモデリング研究集会, 2020年10月22日
  • 粒子追跡モデルを用いた黒潮から沿岸域への物質輸送過程の評価               
    増永 英治; 木村 和久; 小硲 大地; 張 旭; 内山 雄介
    海岸工学講演会, 2020年10月
  • Observations of vertical mixing and sediment heat flux in a shallow lake               
    Eiji Masunaga; Shunsuke Komuro; Tatsumi Kitamura
    JpGU Meeting 2020, 2020年07月
  • Uncertainty of the mixing coefficient investigated with microstructure surveys in coastal oceans               
    Eiji Masunaga
    Ocean Science Meeting 2020, 2020年02月
  • 三陸沿岸海域における多層水塊構造と乱流混合過程               
    増永英治
    日本海洋学会2019年度秋季大会, 2019年09月
  • Mass and heat transport generated by the Kuroshio and tides investigated with a high resolution downscaled regional oceanic,model               
    Eiji Masunaga
    AOGS Meeting 2019, 2019年08月
  • Mass and heat transport generated by the Kuroshio and tides investigated with a high resolution downscaled regional oceanic model               
    Eiji Masunaga
    AOGS Meeting 2019, 2019年08月
  • Mixing and baroclinic structure in a stratified shallow lake, Lake Kasumigaura, Japan               
    Eiji Masunaga
    JpGU Meeting 2019, 2019年05月
  • Nonlinear Internal waves and mixing generated by an interaction of background flows and tides               
    Eiji Masunaga; Yusuke Uchiyama; Hidekatsu Yamazaki
    AGU Fall Meeting 2018, 2018年12月12日
  • 内部潮汐を考慮した伊豆大島周辺海域における潮流予測システムの開発と運用               
    増永英治; 山崎秀勝; 山口邦久
    海岸工学講演会, 2018年11月13日
  • Mixing and sediment transport induced by nonlinear internal wave breaking in coastal regions               
    Eiji Masunaga; Robert S. Arthur; Oliver B. Fringer; Hidekatsu Yamazaki
    PICES Meeting 2018, 2018年11月01日
  • Mixing processes associated with hypoxia in Lake Kasumigaura               
    Eiji Masunaga
    17th World Lake Conference, 2018年10月16日
  • Nonlinear internal waves excited by an interaction of tides and Kuroshio               
    Eiji Masunaga; Yusuke Uchiyama; Hidekatsu Yamazaki
    JpGU-meeting 2018, 2018年05月20日
  • Numerical simulations and observations of nonlinear internal tides in shallow coastal regions.               
    Eiji Masunaga; Robert S. Arthur; Oliver B. Fringer; Hidekatsu Yamazaki
    Ocean Science Meeting 2018, 2018年02月, AGU
  • 黒潮と内部波が影響する伊豆諸島周辺海域における流動場の解明               
    増永英治,鈴江洋太,内山雄介,山崎秀勝
    海岸工学講演会, 2017年10月
  • 非構造格子を用いた東京湾奥における底質輸送過程の高解像度数値シミュレーション               
    増永英治,鯉渕幸雄
    日本海洋学会2017年度秋季大会, 2017年10月
  • Numerical simulations of the interaction between internal waves and the Kuroshio Current over the Izu-Ogasawara Ridge               
    Eiji Masunaga; Guillaume Auger; Matthew Rayson; Oliver Fringer; Hidekatsu Yamazaki
    14th Annual Meeting Asia Oceania Geoscience Society, 2017年08月, AOGS
  • Numerical simulations of internal wave dynamics in the vicinity of Izu-Oshima Island, off Sagami Bay, Japan               
    Eiji Masunaga; Yota Suzue; Yusuke Uchiyama; Hidekatsu Yamazaki
    JpGU-AGU joint meeting, 2017年05月
  • Internal wave-driven sediment transports over contineltal slopes               
    Hidekatsu Yamazaki
    ALSO meegting 2017, 2017年03月
  • 伊豆大島周辺の内部潮汐発生機構               
    増永英治、Oliver Fringer、北出裕二郎、山崎秀勝
    2016年度日本海洋学会春季大会, 2016年03月
  • Generation mechanism and energetics of internalk waves around an island               
    Masunaga; E.; O.B. Fringer; Y. Kitade and H. Yamazaki
    Ocean Science Meeting 2016, 2016年02月26日
  • 浅海域における河川水の混合拡散の観測とモデル化               
    増永英治、Kaushik Sasmal、Adrean Webb、Oliver Fringer; 山崎秀勝
    2015年度日本海洋学会春季大会, 2015年03月
  • YODA Profilerを用いた沿岸海域のおける観測               
    増永英治
    2015年度日本海洋学会春季大会シンポジウムS6海洋乱流測定技術の変遷, 2015年03月
  • Resuspnesion and turbulent mixing due to nonlinear internal bores along a shallow slope               
    Masunaga; E.; H. Yamazaki and T. Nagai
    Ocean Science Meeting 2014, 2014年02月28日
  • Multiple mixing layers and stratification observed in the upper water of Lake Biwa during summer               
    Homma; H.; H. Yamazaki; T. Nagai; E. Masunaga and M Kumagai
    Ocean Science meeting 2014, 2014年02月
  • Resuspension and lateral dispersal of sediments due to shoaling internal waves               
    Masunaga; E.; H. Yamazaki; T. Nagai and O.; Fringer
    2013 6th China-Japan-Korea IMBER Symposium, 2013年10月
  • 斜面上を伝搬する内部波の構造について               
    増永英治、山崎秀勝、長井健容、本間光
    2013年度日本海洋学会春季大会, 2013年03月
  • Development of a new tow-yo instrument to observe detailed river plume structures               
    Masunaga; E.; H. Yamazaki and T. Nagai
    2012 AGU Fall Meeting, 2012年12月
  • Development of a new tow-yo instrument to observe detailed river plume structures               
    Masunaga; E.; H. Yamazaki and T. Nagai
    2012 ASLO Summer meeting, 2012年07月
  • 東京湾北部における内部波と海底傾斜に関する研究               
    増永英治、山崎秀勝、長井健容
    2012年度日本海洋学会春季大会, 2012年03月
  • 新型曳航式観測装置を用いた沿岸の観測に関する研究               
    増永英治、山崎秀勝、長井健容
    2011年度水産海洋学会, 2011年11月
  • 自由落下式CTD(SBPro)による乱流混合強度の推定               
    増永英治、山崎秀勝、岡田知也、柏俊行
    2011年度日本海洋学会春季大会, 2011年03月
  • 曳航式観測装置Sailing Boat Profiler (SBPro) の開発とその応用例               
    増永英治、山崎秀勝、柏俊行、長井健容、野田明、濱田浩明
    2010年度日本海洋学会春季大会, 2010年03月

所属学協会

  • 2017年 - 現在, Asia Oceania Geosciences Society
  • 日本海洋学会
  • 土木学会
  • American Geophysical Union
  • 沿岸域学会

共同研究・競争的資金等の研究課題

  • 河口から大陸棚における流動変動と物質の拡散過程
    学術変革領域研究(A)
    東京大学
    2022年06月 - 2027年03月
  • 洋上風力発電事業の漁業協調共生に係る新モニタリングシステムと魚礁効果予測の開発               
    社会課題解決枠フェーズB(風力発電利用促進分野)
    2022年11月 - 2024年09月
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