| Project/Area Number |
17540408
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Meteorology/Physical oceanography/Hydrology
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| Research Institution | Tohoku University |
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Principal Investigator |
HANAWA Kimio Tohoku University, Graduate School of Science, Professor (40142921)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,440,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥240,000)
Fiscal Year 2007: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2006: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2005: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | reemergence / sea surface temperature / Aleutian Low / North Pacific Subtropical Mode Water / North Pacific Eastern Subtropical Mode Water / climate variation / subtropical gyre / Kuroshio / 遠隔再出現 / 冬季偏西風 / 海洋表層貯熱量 / Argoフロート / WHPデータ / ソルトフィンガー / 再出現機構 / 亜熱帯モード水 / 中央モード水 / 東部亜熱帯モード水 / 海面熱フラックス / 遠隔型再出現 |
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| Research Abstract |
The purpose of the present study is to investigate the reemergence phenomenon of the North Pacific Subtropical Mode Water (NPSTMW) in detail and to clarify its relation to the 20-year period Pacific Oscillation. The present research result can be summarized as follows.
1. The NPSTMW has both co-located reemergence in the formation area and remote reemergence in the central North Pacific due to the advection of part of NPSTMW.
2. It is found that the Eastern Subtropical Mode Water shows no reemergence phenomenon mainly due to quick change in water properties by the vigorous mixing of salt-finger type convection and weak heat input in the warming season.
3. Remote emergence phenomenon has 20-year periodicity, the reason of which is 20-year periodicity of the Aleutian Low activity.
The above result strongly suggests that the remote reemergence phenomenon of the NPSTMW Pacific sector. The scenario of the 20-year periodic climate variation is as follows. The strengthened Aleutian Low causes the spin-up of the subtropical gyre, and resultantly the NPSTMW is formed more with some time delay. Then, the remote emergence occurs in the central North Pacific and sea surface temperature (SST) is warmed there. This SST change would cause the weakening of the Aleutian Lows. The same process with a sign reversed would follow. The period to close one cycle is about 20 years.
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