北太平洋中層水の形成・輸送・変質過程に関する研究  [in Japanese] Studies on the formation, transport and modification of North Pacific Intermediate Water  [in Japanese]

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Abstract

<p>北太平洋中層水の形成・輸送・変質過程について受賞者の研究を総括した。厚い低温低塩分水塊が,海氷形成に伴う陸棚高密度水沈降や千島列島付近の強い乱流鉛直混合に影響されて形成される。このオホーツク海モード水が太平洋へ流出し,薄い太平洋水と混合して親潮水が形成される。厚い性質を保持した親潮水の一部は,北海道・東北沿岸を南下し,黒潮続流と合流・混合して,北太平洋中層水を更新する。黒潮水と親潮水の等密度面混合は,厚い中層親潮水に起因する不安定によって促進される。北太平洋中層水は,亜熱帯循環に沿って輸送され北太平洋亜熱帯循環域に広く分布する。その北端部分は,移行領域と呼ばれる海域で低塩分亜寒帯水が表層に層重し,塩分極小が消失した海水が,アラスカ湾に流れ込み,北太平洋亜寒帯海域での中暖構造を作る。北太平洋亜寒帯中層は,この高温高塩分水の流入とオホーツク海での低温低塩分水の流入でほぼバランスしている。千島列島付近やアリューシャン列島付近の潮汐に起因する乱流鉛直混合は,水塊変質と変動に大きな影響を与える。潮汐18.6年周期変調は水塊変動の一因であり,海洋を通じて気候にも影響を与えている。</p>

<p>Studies on North Pacific Intermediate Water (NPIW) by the author were reviewed as a lecture of 2011 JOS-prize. Thick, cold and low-salinity intermediate water-mass (Okhotsk Sea Mode Water) is formed through dense shelf water sinking in the Okhotsk Sea, largely influenced from strong turbulent vertical mixing around the Kuril Straits. This thick water mass flows out to the Pacific and is mixed with thin Pacific water to form Oyashio water. Significant amount of Oyashio water which retains the thick water mass flows along the east coast of Hokkaido and Honshu, and merge and mix with the Kuroshio Extension, to form new NPIW. The isopycnal mixing near the Kuroshio Extension is enhanced by instability caused by the intermediate thick Oyashio water. The new NPIW flows along the large scale subtropical gyre circulation, and a part loses its intermediate salinity minimum structure in the Transition Domain by overlying low-salinity subarctic water and developed deep mixed layer. This water flows into the Alaskan Gyre and feed the mesothermal (temperature vertical maximum) structure in the subarctic North Pacific. In the intermediate layer in the north Pacific subarctic gyre, supply of this warm and saline water is mostly balanced with cold and low salinity dense water supply in the Okhotsk Sea. The strong turbulent mixing around the Kuril and Aleutian Straits etc. has strong impact on modification and long-term variations of water masses. 18.6-year period tidal cycle is a cause of water-mass variability, and eventually possibly leads to bidecadal variations of ocean and climate.</p>

Journal

  • Oceanography in Japan

    Oceanography in Japan 21(3), 83-99, 2012-05-15

    The Oceanographic Society of Japan

References:  112

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Codes

  • NII Article ID (NAID)
    110009457766
  • NII NACSIS-CAT ID (NCID)
    AN10382760
  • Text Lang
    JPN
  • Article Type
    ART
  • ISSN
    09168362
  • NDL Article ID
    023844140
  • NDL Call No.
    Z15-778
  • Data Source
    CJP  NDL  NII-ELS  J-STAGE 
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