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第 140 回 大気海洋圏物理系セミナー のおしらせ

日 時: 11月 18日(木) 午前 9:30
場 所:低温科学研究所 2階 講義室

発表者:二橋 創平 研究員 (低温科学研究所 寒冷海洋圏科学部門 )
題 目:Observational evidence of a hemispheric-wide ice-albedo feedback effect on Antarctic sea-ice decay

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Observational evidence of a hemispheric-wide ice-albedo feedback effect on Antarctic sea-ice decay (二橋 創平 研究員) 発表要旨 :

  
  The effect of ice-albedo feedback on sea-ice decay is demonstrated 
 for the entire Antarctic Ocean from an analysis of satellite-derived 
 hemispheric sea-ice maps and ERA-40 atmospheric data for the period 
 1978-2001. Wind-forced ice drift at the beginning of the melt season 
 (November) correlate with ice concentration at the time of most active 
 melt (December). Standard deviations of ice concentration are  
 amplified as sea-ice melts toward the time of maximum melt. These 
 findings can be explained as follows: once ice concentration is 
 decreased (increased) by the divergent (convergent) wind at the 
 beginning of the melt season, solar heating through the increased 
 (decreased) open water fraction is enhanced (reduced), leading to 
 (suppressing) a further decrease in ice concentration by the heat.  
 A simple ice-ocean coupled model also supports this hypothesis. This 
 positive feedback mechanism can partly explain the large interannual 
 variability of the sea-ice cover in the summer Antarctic Ocean. 
  

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連絡先

川島 正行 @北海道大学大学院地球環境科学研究科
大気海洋圏環境科学専攻 物理系
mail-to:kawasima@lowtem.hokudai.ac.jp / Tel: 011-706-6885