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グリーンランド南東ドームにおける浅層アイスコア掘削と初期物理解析
飯塚, 芳徳;的場, 澄人;藤田, 秀二;新堀, 邦夫;山崎, 哲秀;宮本, 淳;堀, 彰;斉藤, 健;古川, 崚仁;杉山, 慎;青木, 輝夫
Permalink : http://hdl.handle.net/2115/65082
JaLCDOI : 10.14943/lowtemsci.75.45
KEYWORDS : グリーンランド氷床;南東ドーム;アイスコア;圧密氷化
Abstract
グリーンランドにおける高涵養量域の圧密氷化過程の特徴の解明や近年の人為起源エアロゾルの変遷の解読を目的として，2015 年5 月にグリーンランド南東ドームにおいて，90.45 m の浅層コア掘削を実施した．掘削地点はタシーラク（アンマサリック）から185 km 北に位置している（SE-Dome；67.18°N，36.37°W，3170 m a.s.l.）．掘削孔の氷温は20 m 深において－20.9℃であった．2015年8月にコアが日本に輸送され，低温科学研究所の低温室において密度測定や電気伝導度測定などの初期コア解析が行われた．その結果，SE-Dome コアの氷化深度は83-86 m，涵養量は約1.0 m w.e. yr－1 であった．SE-Dome コアは氷床のドームとしては最も高涵養量の地域の一つである．圧密氷化過程を調べたところ，750 kg m－3 以上の密度域において，SE-Dome コアは通常の涵養量地域の浅層コアよりも変形しやすい特徴を持つことが分かった．
In order to understand 1) temporal variations of anthropogenic aerosols from European regions under the Icelandic Low with high time resolution, and 2) the snow densification mechanism at a high accumulation dome in Greenland, we drilled a 90.45 m ice core in a high accumulation area of the southeastern Greenland Ice Sheet. The drilling site (SE-Dome; 67.18°N, 36.37°W, 3170 m a.s.l.) is located 185 km north of the town of Tasiilaq in southeastern Greenland. The ice temperature is -20.9℃ at 20 m depth, and the site has an average accumulation rate of 1.0 m w.e. yr-1 in water equivalent. The ice core exhibits distinct firn densification. The close-off density of 830 kg m-3 occurs at 83.4-86.8 m depth, which is about 20 m shallower than predicted from an empirical model. In the region where the density ρ＞750 kg m-3, the densification appears faster than according to the empirical model.
In order to understand 1) temporal variations of anthropogenic aerosols from European regions under the Icelandic Low with high time resolution, and 2) the snow densification mechanism at a high accumulation dome in Greenland, we drilled a 90.45 m ice core in a high accumulation area of the southeastern Greenland Ice Sheet. The drilling site (SE-Dome; 67.18°N, 36.37°W, 3170 m a.s.l.) is located 185 km north of the town of Tasiilaq in southeastern Greenland. The ice temperature is -20.9℃ at 20 m depth, and the site has an average accumulation rate of 1.0 m w.e. yr-1 in water equivalent. The ice core exhibits distinct firn densification. The close-off density of 830 kg m-3 occurs at 83.4-86.8 m depth, which is about 20 m shallower than predicted from an empirical model. In the region where the density ρ＞750 kg m-3, the densification appears faster than according to the empirical model.
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