Outline of study results obtained by the group #5 of the GRENE Arctic Climate Research Project

第6回極域科学シンポジウム特別セッション：[S] 北極温暖化とその影響 ―GRENE 北極気候変動プロジェクトと新しい方向性―11月18日（水）　国立極地研究所 2階 大会議

A supersolutions perspective on hypercontractivity

The purpose of this article is to expose an algebraic closure property of supersolutions to certain diffusion equations. This closure property quickly gives rise to a monotone quantity which generates a hypercontractivity inequality. Our abstract argument applies to a general Markov semigroup whose generator is a diffusion and satisfies a curvature condition.Comment: 7 page

Simulation of CO2 and CH4 seasonal cycles in Siberia

第6回極域科学シンポジウム分野横断セッション：[IA] 急変する北極気候システム及びその全球的な影響の総合的解明―GRENE北極気候変動研究事業研究成果報告2015―11月19日（木）　国立極地研究所 2階 大会議

Discussion of the reliability of CO2, CH4 and N2O records from polar ice cores (scientific paper)

Air in polar ice has about the same composition as atmospheric air at the time of ice formation. This allows to determine the composition, especially the concentration of greenhouse gases, in the past. However, the air composition in the ice can be slightly altered by chemical and biological processes in the ice. The reliability of long term trends can be determined by comparing records from different ice cores. For short duration details and time lags such comparisons are not possible due to uncertainties of the age scales of records from different cores. In this case very detailed records along sections of ice cores show whether the scatter of the results is larger than the theoretical expected one. A larger scatter is assumed to be caused by reactions between impurities in the ice which show generally short term variations. A low scatter of detailed high resolution records is therefore, a prerequisite for reliable records

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

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\u27s

Development of a continuous measurement system for atmospheric N2O and CO concentrations and its application to in-situ observation at Syowa Station, Antarctica

The Tenth Symposium on Polar Science/Ordinary sessions: [OM] Polar Meteorology and Glaciology, Wed. 4 Dec. / Entrance Hall (1st floor) , National Institute of Polar Researc