日本地球惑星科学連合2018年大会

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セッション記号 A (大気水圏科学) » A-CC 雪氷学・寒冷環境

[A-CC29] アイスコアと古環境モデリング

2018年5月22日(火) 09:00 〜 10:30 201A (幕張メッセ国際会議場 2F)

コンビーナ:植村 立(琉球大学 理学部)、川村 賢二(情報・システム研究機構 国立極地研究所)、阿部 彩子(東京大学大気海洋研究所、共同)、竹内 望(千葉大学)、座長:竹内 望(千葉大学)、服部 祥平(東工大)

09:15 〜 09:30

[ACC29-02] グリーンランド南東部、高涵養量ドームにおける浅層アイスコアプロジェクトの概要と研究成果

★招待講演

*飯塚 芳徳1的場 澄人1古川 崚仁1安藤 卓人1斉藤 健1Parvin Fahmida1網野 智美1柴田 麻衣1門田 萌1関 宰1杉山 慎1植村 立2藤田 耕史3鶴田 明日香4服部 祥平4藤田 秀二5本山 秀明5永塚 尚子5大藪 幾美5山口 悟6安達 聖6大野 宏7堀 彰7宮本 千尋8高橋 嘉夫8佐々木 千晶9鈴木 利孝9Bautista VII Angel10,11松崎 浩之10堀内 一穂12宮本 淳13芳村 圭14Sjolte Jesper15庭野 匡思16大島 長16橋本 明弘16山崎 哲秀17青木 輝夫18 (1.北海道大学低温科学研究所、2.琉球大学理学部、3.名古屋大学環境学研究科、4.東京工業大学物質理工学院応用化学系、5.国立極地研究所、6.防災科学技術研究所、7.北見工業大学社会環境工学科、8.東京大学大学院理学系研究科、9.山形大学大学院理工学研究科、10.東京大学 大学院工学系研究科、11.フィリピン核研究所、12.弘前大学理工学研究科、13.北海道大学高等教育推進機構、14.東京大学生産技術研究所、15.ルンド大学第四紀地理学教室、16.気象庁気象研究所、17.アバンナック、18.岡山大学自然科学研究科)

キーワード:アイスコア、グリーンランド、高涵養

On May 2015, 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 [1]. Then we measure physical and chemical properties of the SE-Dome ice core. Based on the measurements, we show the general characteristics of the SE-Dome ice core. I) As for dating of the ice core [2], we propose a dating method based on matching the δ18O variations between ice-core records and records simulated by isotope-enabled climate models. We applied this method to a δ18O record from the SE-Dome ice core. The close similarity between the δ18O records from the ice core and models enables correlation and the production of a precise age scale, with an accuracy of a few months. II) As for physical property [3], the ice was –20.9 ºC at 20-m depth. The close-off density of 830 kg m-3 occurs at 83.4–86.8-m depth, which is about 20-m shallower than that obtained from empirical models, indicating that the firn with a higher density is softer than that from empirical result. We interpret that the high accumulation rate creates a high overburden pressure in a short time. The relative softness of the firn may arise from 1) there being not enough time to form bonds between grains as strong as those in a lower accumulation-rate area, and similarly, 2) the dislocation density in the firn being relatively high. III) As for chemical property [4], we measured the major ion fluxes, and obtained records of annual ion fluxes from 1957 to 2014. We find a high average NO3- flux (1.13 mmol m-2 yr-1) in the ice core, which suggests a negligible effect from post-depositional NO3- loss, indicating the SE-Dome region is an excellent location for reconstructing nitrate fluxes. For the non-sea-salt (nss) SO42- and NH4+ fluxes, a decreasing and increasing trend from 1970 to 2010, respectively, tracks well with the anthropogenic SOx and NH3 emissions. In contrast, the decadal trend of NO3- flux differs from the decreasing trend of anthropogenic NOx emissions. We continue to investigate the paleoenvironment with multi proxies from several analyses (e.g. [5]) of the high-time-resolution and chemicals-well-preserved ice core.

References
[1] Iizuka et al., (2016). Bulletin of Glaciological Research, 34, 1–10. https://doi.org/10.5331/bgr.15R03
[2] Furukawa et al., (2017). Journal of Geophysical Research: Atmospheres, 122, 10,873–10,887. https://doi.org/10.1002/2017JD026716
[3] Iizuka et al., (2017). Arctic, Antarctic, and Alpine Research, 49, 13–27. https://doi.org/10.1657/AAAR0016-034
[4] Iizuka et al., (2018). Journal of Geophysical Research: Atmospheres, 123. https://doi.org/10.1002/2017JD026733
[5] Bautista et al., (2018) Journal of Environmental Radioactivity 184–185, 14–21, https://doi.org/10.1016/j.jenvrad.2017.12.015