南極ドームふじ深層掘削孔の検層における液温測定値の評価と補正

第6回極域科学シンポジウム[OM] 極域気水圏11月16日（月）　国立極地研究所１階交流アトリウ

Improvement of drill system for the third deep ice coring project around Dome Fuji, Antarctica - Focusing on selection of drilling fluids -

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

Characterization of Lanthanum(III) Chromium(V) Tetraoxide by X-Ray Photoelectron Spectroscopy

Lanthanum(III) chromium(V) tetraoxide, LaCrO4, was synthesized by a thermal decomposition method and characterized by X-ray photoelectron spectroscopy and ab initio molecular orbital calculations. The chromium(V) state in LaCrO4 is stable in both air and vacuum. The electron binding energies, EB, and Auger parameters, α, of Cr(V) and La(III) indicated that the covalency of the Cr-O bonds in CrO4 tetrahedra is higher than that in CrO6 octahedra of LaCrO3, and that La(III) in LaCrO4 is more ionic than in LaCrO3. The results of ab initio molecular orbital calculations agreed with the measured characteristics, that is, the electrons are flowing from oxygen to Cr(V) and the covalency plays a significant part in the Cr-O bonds. This behavior of the Cr-O bond was considered to contribute to stabilizing CrO43- tetrahedra

State dependence of climatic instability over the past 720,000 years from Antarctic ice cores and climate modeling

過去72万年間の気候の不安定性を南極ドームふじアイスコアの解析と気候シミュレーションにより解明. 京都大学プレスリリース. 2017-02-10.Climatic variabilities on millennial and longer time scales with a bipolar seesaw pattern have been documented in paleoclimatic records, but their frequencies, relationships with mean climatic state, and mechanisms remain unclear. Understanding the processes and sensitivities that underlie these changes will underpin better understanding of the climate system and projections of its future change. We investigate the long-term characteristics of climatic variability using a new ice-core record from Dome Fuji, East Antarctica, combined with an existing long record from the Dome C ice core. Antarctic warming events over the past 720, 000 years are most frequent when the Antarctic temperature is slightly below average on orbital time scales, equivalent to an intermediate climate during glacial periods, whereas interglacial and fully glaciated climates are unfavourable for a millennial-scale bipolar seesaw. Numerical experiments using a fully coupled atmosphere-ocean general circulation model with freshwater hosing in the northern North Atlantic showed that climate becomes most unstable in intermediate glacial conditions associated with large changes in sea ice and the Atlantic Meridional Overturning Circulation. Model sensitivity experiments suggest that the prerequisite for the most frequent climate instability with bipolar seesaw pattern during the late Pleistocene era is associated with reduced atmospheric CO2 concentration via global cooling and sea ice formation in the North Atlantic, in addition to extended Northern Hemisphere ice sheets