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

Photosynthetic physiology and primary productivity of phytoplankton in the Australian sector of the Southern Ocean

第2回極域科学シンポジウム　共通セッション「海氷圏の生物地球化学」 11月16日（水） 統計数理研究所 3階セミナー

The effect of pCO2 on size-fractionated phytoplankton community in the Southern Ocean

第3回極域科学シンポジウム　横断セッション「南極海季節的海氷域における生物地球化学」11月26日（月） 統計数理研究所 セミナー

Improved scientific ballooning applied to the cryo-sampling experiment at Syowa Station

On January 3, 1998, a large balloon (30000 m^3) was successfully launched at Syowa Station for the cryo-sampling of the stratospheric atmosphere. The sampling system splashed down in the Liitzow-Holm Bay and recovered by icebreaker SHIRASE. The cryo-sampling at Antarctica was the first trial in the world and the recovery of a heavy payload was also the first challenge at Syowa Station. A lot of new ballooning technologies were applied to this operation, such as compact balloon launching equipments, a reliable recovery system, a handy ground radio station for the balloon tracking and data acquisition and so forth. The realtime flight data could be received at National Institute of Polar Research (NIPR) in Tokyo by using the computer network via INMARSAT. At NIPR the collaboration members could monitor the entire process of the experiment at Syowa Station in detail and send some instructions and advice. This balloon experiment showed an extended possibility of a large scale scientific ballooning at Syowa Station. This paper deals with those newly developed balloon engineering technologies