CESD Seminar

１０月２９日月曜日に、地球表層圏変動研究センターと海洋底科学部門では、以下のセミナーを開催致します。今回はハワイ大学のAxel Timmerman教授にお話頂きます。
会場へのアクセスについては以下をご参照ください。
http://lams-yokoyama.blogspot.jp/search/label/DiaryのLinks欄にある”大気海洋研究所のアクセス（１１月変更）”

日時）
2012年10月29日（月）16:00～17:00
場所）　東京大学大気海洋研究所　217号室
〒277-8564　千葉県柏市柏の葉5-1-5
共催）東京大学大気海洋研究所地球表層圏変動センター, PAGES, INQUA commission of Coastal and Marine Processes, JAMSTEC
問い合わせ先）横山祐典（yokoyamaのaori.u-tokyo.ac.jp：「の」を「@」にしてください）
プログラム）
- Exploring the Dynamics of Glacial Cycles using a newly developed Earth System Model
  (Axel Timmermann)
  Glacial cycles with timescales of 80-100 thousand years are one of the largest climate signals in the geological record of the Cenozoic. Whereas the role of orbitally-induced solar insolation changes in pace-making glacial cycles, has been recognized since more than hundred years, the detailed physical mechanisms of how insolation variations translate into the waxing and waning of massive inland ice-sheets still remain elusive. This talk will present first results from a newly developed 3-dimensional coupled ice-sheet climate model that is capable of simulating glacial cycles in response to orbital and greenhouse gas forcing. A brief summary of general ice-sheet-climate modeling issues (including mass balance, albedo, initialization, model biases and multiple equilibria) will be followed by an extensive discussion of the mechanisms that lead to the build-up of Northern Hemisphere ice-sheets and their demise. Our results support the notion that changes in boreal summer insolation and greenhouse gases are essential in triggering deglacial ice-sheet retreat in the Northern Hemisphere. The model simulations further illustrate that orbital forcing in austral spring strongly affects the Southern Hemispheric sea-ice extent, which in turn modulates the efficiency of Ekman pumping in the Southern Ocean. This process controls the upwelling of DIC-rich waters, hence contributing to the glacial variability in atmospheric CO2 concentrations. According to this scenario the dynamics of Northern Hemisphere ice-sheets is then determined by the local orbital forcing as well as by the CO2 changes -- the latter originating from orbitally-modulated processes in the Southern Hemisphere.

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