Reconstruction of past atmospheric CH4 concentration from the firn air data at Dome Fuji (scientific note)

元データ 国立極地研究所

概要

Air samples were collected from different depths of the firn layer at Dome Fuji in December 1998 and analyzed for CH4 concentrations. The age distribution of CH4 in the firn was calculated by using a one-dimensional numerical model, and then the inverse method was applied to reconstruct variations of atmospheric CH4 in the past. The age distribution function was calculated by including processes of molecular diffusion, downward air advection and bubble trapping in the snow-ice transition zone. Once the age distribution function is calculated, the vertical distribution of CH4 in the firn layer can be reconstructed by a linear combination of the age distribution functions weighted by the atmospheric CH4 concentrations in the past. Therefore, the most plausible past atmospheric record of CH4 can be derived iteratively so that its observed profile in the firn layer was reproduced well. In order to check the calculation scheme, the estimated variation of atmospheric CH4 was compared with direct measurements in the Antarctic region. They were in good agreement with each other, even for rapid slowing down of the secular increase observed in the 1990's.

著者

Kawada Kunio Center For Atmospheric And Oceanic Studies Graduate School Of Science Tohoku University
張 紀久夫 阪大基:福井工大工
Kawamura Kenji Center For Atmospheric And Oceanic Studies Graduate School Of Science Tohoku University
Kamiyama K National Institute Of Polar Research Research Organization Of Information And Systems
Hashida Gen National Institute Of Polar Research
Nakazawa Takakiyo Center for Atmospheric and Oceanic Studies, Tohoku University
Aoki Shuji Center for Atmospheric and Oceanic Studies, Tohoku University
Nakazawa Takakiyo Center For Atmospheric And Oceanic Studies Graduate School Of Science Tohoku University
Aoki Shuji Center For Atmospheric And Oceanic Studies Graduate School Of Science Tohoku University
AOKI Shuhji National Institute of Polar Research
Aoki S Center For Atmospheric And Oceanic Studies Graduate School Of Science Tohoku University
Kawamura K Center For Atmospheric And Oceanic Studies Tohoku University
Kawada K Toyama Univ. Toyama
清水 明 東大教養
Aoki Shuji Center For Atmospheric And Oceanic Studies Graduate School Of Sci. Tohoku Univ.
Aoki Shuhji Faculty Of Science Tohoku University
Aoki Syuji National Institute Of Polar Research
清水 明 東大院総合文化・科技団
Sugawara Satoshi Institute of Earth Science,Miyagi University of Education
Kawada Kunio Department Earth Science Toyama University
Kamiyama Kokichi National Institute Of Polar Research Research Organization Of Information And Systems
Nakazawa Takakiyo Center For Atmospheric And Oceanic Studies Graduate School Of Sci. Tohoku Univ.
Nakazawa Takakiyo Center For Atmospheric And Oceanic Studies Faculty Of Science
清水 明 Center For Atmospheric And Oceanic Studies Graduate School Of Science Tohoku University
Nakazawa T Center For Atmospheric And Oceanic Studies Faculty Of Science
Sugawara Satoshi Institute Of Earth Science Miyagi University Of Education
SHIMIZU Akira Deparment of Physics, Rikkyo University

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