富山湾周辺海域における表層流の季節変化  [in Japanese] Seasonal Variations of Surface Flow around Toyama Bay  [in Japanese]

Search this Article

Author(s)

Abstract

対馬暖流の沿岸分枝流の形成には陸棚地形が重要な役割を果たしているが,この分枝流の流路にある陸棚域は富山湾周辺で一端途切れている。過去の水温データ解析から,富山湾の東側における分枝流は沖合へ離岸した傾圧流と推測されているが,実際の流れのパターンとその季節変化については明らかにされていない。本研究では,長期間に蓄積されたGEK(Geomagnetic Electrokineto Graph)・ADCP(Acoustic Doppler Current Profiler)・沿岸水位のデータを用いて,富山湾周辺海域における表層流の季節変化を解析した。佐渡島(小木)と日本列島沿岸(輪島,富山,柏崎)における水位差の季節変化には,東向き表層流の強まる時期が7月と11月の2回あることが示された。この結果をもとに,一年間を5季節に区分し,GEK・ADCP両データを用いて表層流の季節空間分布図を作成した。まず,年間を通した流れとして,"能登半島の西側における39°N付近を境界とした東向き沖合流と,日本列島付近の東向き沿岸流とに二分岐した流れが,佐渡島周辺(能登半島の東側)で合流する",と特徴付けられる流れのパターンが認められた。すなわち,佐渡島の西側には一年を通して北東流が存在する。一方,富山湾周辺における流れパターンには明瞭な季節変化が示され,その流れ解析の空間解像度を高めることによって,二つの流れパターンの存在も明らかに示された。その第一の流れは富山湾内へ流入する流れ(湾の西側に沿った沿岸分枝流)であり,4月~9月に顕著にみられ,9月には弱まる。そして,他の流れは湾口を横断する流れ(能登半島北部から佐渡海峡に向かう傾圧流)で年間を通して存在し,湾内流入流が消滅後の秋季に最も明瞭になることも判明した。The shelf topography plays an important role in the formation of the coastal branch flow of the Tsushima Warm Current. This shelf breaks a part of the branch flow around Toyama Bay. Although its path east of Toyama Bay has been inferred as the offshore baroclinic flow from temperature distributions, its flow pattern and seasonal variability around Toyama Bay have not been clarified. By using long-term GEK, ADCP and sea level data, we describe the seasonal change of surface current around the Bay. Sea level differences between Sado Is. (Ogi) and coastal stations (Wajima, Toyama, Kashiwazaki) reveal that there are two periods in which the eastward surface current velocity is enhanced in July and November. Based on this feature, we classify the annual cycle into five seasons in order to examine temporal change in spatial distributions of surface flow using GEK and ADCP data. The annual common flow pattern shows that there are two main paths, the one consisting of the eastward offshore flow (the boundary being 39°N latitude) and the other. a coastal branch flow on the Japanese shelf joining near Sado Is (east of Noto Peninsula). This means that there is the northward flow west of Sado Is. throughout the year. On the other hand, the flow pattern around Toyama Bay has a prominent seasonal cycle, and our gridded current field with fine spatial resolution shows that there are actually two flow patterns. One is the inflow into Toyama Bay (the near-shore branch along the western bay coast) which is identified in April to September and weakens in September. The other is a flow across the bay mouth (the baroclinic flow from the north of Noto peninsula into Sado strait), which exists throughout the year and is clearly seen in autumn after the disappearance of Toyama Bay inflow.

Journal

  • Oceanography in Japan

    Oceanography in Japan 16(4), 291-304, 2007-07-05

    日本海洋学会

References:  9

Cited by:  6

  • Sea level difference inducing the passage-flow through the Tsugaru Strait  [in Japanese]

    IINO Rieko , ISODA Yutaka , YAHABA Hiroshi

    海と空 85(1), 1-19, 2009-06-30

    References (15)

  • Seasonal Variations of Water System Distributions and Flow Patterns off the West Coast of Hokkaido  [in Japanese]

    HIGAKI Naoyuki , ISODA Yutaka , ISOGAI Yasuhiro , YAHABA Hiroshi , Naoyuki Higaki , Yutaka Isoda , Yasuhiro Isogai , Hiroshi Yahaba , 北海道立地質研究所 , 北海道大学大学院水産科学研究院 , 北海道大学大学院水産科学研究院 , 北海道大学大学院水産科学研究院 , Geological Survey of Hokkaido , Graduate School of Fisheries Sciences Hokkaido University , Graduate School of Fisheries Sciences Hokkaido University , Graduate School of Fisheries Sciences Hokkaido University

    Oceanography in Japan 17(4), 223-240, 2008-07-05

    References (28) Cited by (2)

  • The Subsurface Counter-flow along the Offshore Side of the Soya Warm Current in Spring  [in Japanese]

    ABE Shoko , ISODA Yutaka , YAHABA Hiroshi , Shoko Abe , Yutaka Isoda , Hiroshi Yahaba , 北海道大学大学院環境科学院 , 北海道大学大学院水産科学研究院 , 北海道大学大学院環境科学院 , Graduate School of Environmental Science Hokkaido University , Graduate School of Fisheries Sciences Hokkaido University , Graduate School of Fisheries Sciences Hokkaido University

    Oceanography in Japan 18(4), 265-286, 2009-07-05

    References (21)

  • Seasonal Variations of Surface Flow Patterns in the Nemuro Strait  [in Japanese]

    MORI Fumihiro , ISODA Yutaka , ABE Syoko , KOBAYASHI Naoto , YAHABA Hiroshi , ISOGAI Yasuhiro , Fumihiro Mori , Yutaka Isoda , Syoko Abe , Naoto Kobayashi , Hiroshi Yahaba , Yasuhiro Isogai , 北海道大学大学院環境科学院 , 北海道大学大学院水産科学研究院 , 北海道大学大学院環境科学院 , 北海道大学水産学部 , 北海道大学大学院水産科学研究院 , 北海道大学大学院水産科学研究院 , Graduate School of Environmental Science Hokkaido University , Graduate School of Fisheries Sciences Hokkaido University , Graduate School of Environmental Science Hokkaido University , Faculty of Fisheries Sciences Hokkaido University , Graduate School of Fisheries Sciences Hokkaido University , Graduate School of Fisheries Sciences Hokkaido University

    Oceanography in Japan 19(2), 89-110, 2010-03-15

    References (15) Cited by (1)

  • Variability of summer water-mass structure in Toyama bay coastal-zone  [in Japanese]

    WATANABE Yoshimi , MATSUURA Tomonori , CHIBA Hajime , Yoshimi Watanabe , Tomonori Matsuura , Hajime Chiba , 富山大学大学院理工学教育部:(現)一般財団法人沿岸技術研究センター , 富山大学大学院理工学研究部 , 富山高等専門学校商船学科 , Faculty of Science/Graduate School of Science and Engineering University of Toyama:(Presnt office)Coastal Development Institute to Technology , Faculty of Science/Graduate School of Science and Engineering University of Toyama , Department of Maritime Technology Toyama National College of Technology

    Oceanography in Japan 22(4), 97-117, 2013-07-15

    J-STAGE  References (18)

  • Hydrographic conditions northwest off the Noto Peninsula in the Japan Sea and its importance to the monitoring of the Tsushima Current  [in Japanese]

    SENJYU Tomoharu , OOKEI Noriyuki

    海と空 87(2), 33-48, 2012-03-16

    References (33)

Codes

  • NII Article ID (NAID)
    110006317527
  • NII NACSIS-CAT ID (NCID)
    AN10382760
  • Text Lang
    JPN
  • Article Type
    Journal Article
  • ISSN
    09168362
  • NDL Article ID
    8883039
  • NDL Source Classification
    ZM44(科学技術--地球科学--海洋・陸水・火山)
  • NDL Call No.
    Z15-778
  • Data Source
    CJP  CJPref  NDL  NII-ELS 
Page Top