第4回極域科学シンポジウム個別セッション：[OB] 生物圏11月12日（火）13:00-14:00　国立国語研究所 ２階ラウン

Bruno Delille

Gerhard S. Dieckmann

Jean-Louis Tison

Klaus M. Meiners

Mats A. Granskog

田村 岳史

野村 大樹

National Institute of Polar Research Repository

  冬季南極海における大気−海氷間の二酸化炭素交換	   野村大樹 1, 2, 3, Bruno Delille 4, Gerhard S. Dieckmann 5, Jean-Louis Tison 6,  Klaus M. Meiners 7, 8, Mats A. Granskog 3, 田村岳史 9   1北大低温研 2学振 3ノルウェー極地研 4リエージュ大学 5アルフレッド・ウェゲナー極地海洋研	  6ベルギー自由大学 7タスマニア大学 8オーストラリア南極局 9極地研    Sea ice CO2 flux in the Southern Ocean during mid-winter and early spring   Daiki Nomura 1, 2, 3, Bruno Delille 4, Gerhard S. Dieckmann 5, Jean-Louis Tison 6,  Klaus M. Meiners 7, 8, Mats A. Granskog 3, Takeshi Tamura 9   1 Institute of Low Temperature Science, Hokkaido University 2 Japan Society for the Promotion of Science 3 Norwegian Polar Institute 4 Université de Liège 5 Alfred Wegener Institute for Polar and Marine Research 6 Université Libre de Bruxelles 7 University of Tasmania 8 Australian Antarctic Division  9 National Institute of Polar Research   There seems little doubt that sea ice is permeable to CO2 and other gases although air–sea ice gas flux is more or less inhibited at a brine volume fraction of less than 5% representing the threshold for fluid permeability of sea ice. Generally, air–sea ice CO2 flux is at its minimum in winter due to low sea ice temperatures and consequently reduced permeability despite the fact the partial pressure of CO2 in sea ice is usually high at that time and sea ice has therefore the potential to release CO2 to the atmosphere. Here, we present first evidence that snow laden Antarctic sea ice can act as source for atmospheric CO2 even during mid-winter and early spring. During a mid-winter cruise to the Weddell Sea (AWECS, 2013) and an early spring cruise off east Antarctica (SIPEX-2, 2012), due to thick insulating snow covers, the bottom of the snow and the surface of the sea ice were relatively warm (>–10°C) even though air temperature was sometimes below –30°C. In addition, in both areas, sea ice was characterized by high bulk-salinities, resulting in brine volume fractions that are generally higher than 5%. Automatic “open-closed” chamber measurements indicated positive CO2 fluxes of up to +2.5 mmol C m–2 day–1, illustrating that sea ice acted as a source of atmospheric CO2. Higher fluxes were measured at bare ice surfaces after removing the snow. However, generally low snow densities (mean: 339 kg m–3), indicating a permeable snow cover, facilitated degassing of CO2 at the snow-air interface. Our results therefore suggest that even in the winter and early spring, Antarctic sea ice can act as CO2 source for the atmosphere, particularly in areas with a thick insulating snow cover.   

Sea ice CO2 flux in the Southern Ocean during mid-winter and early spring

https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=11592&item_no=1&attribute_id=16&file_no=1

Sea ice CO2 flux in the Southern Ocean during mid-winter and early spring

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National Institute of Polar Research Repository