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Histories of atmospheric N2O concentration and its δ15N and δ18O were reconstructed for the period 1952–2001 on the basis of the analyses of firn air collected at the North Greenland Ice Core Project (NGRIP), Greenland, and Dome Fuji and H72, Antarctica. The N2O concentration increased from 290 ppbv in 1952 to 316 ppbv in 2001, which agrees well with the results from atmospheric observations and polar ice core analyses. The δ15N and δ18O showed a secular decrease, the respective values being 8.9 and 21.5‰ in 1952 and 7.0 and 20.5‰ in 2001. Their rates of change also varied, from about −0.02‰ yr−1 in the 1950s to about −0.04‰ yr−1 in 1960–2001 for δ15N, and from about 0‰ yr−1 to −0.02‰ yr−1 for δ18O. The isotopic budgetary calculations using a two‐box model indicated that anthropogenic N2O emission from soils played a main role in the atmospheric N2O increase after industrialization, as well as that the average isotopic ratio of anthropogenic N2O has potentially been changed temporally.

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As a basic understanding of the dynamics of the atmospheric circulation, it has been believed that gravitational separation of atmospheric components is observable only in the atmosphere above the turbopause. However, we found, from our high-precision measurements of not only the isotopic ratios of N₂, O₂ and Ar but also the mole fraction of Ar, that gravitational separation occurs even in the stratosphere below the turbopause; their observed vertical profiles are in good agreement with those expected theoretically from molecular mass differences. The O₂/N₂ ratio observed in the middle stratosphere, corrected for gravitational separation, showed the same mean air age as estimated from the CO₂ mole fraction. Simulations with a 2-dimensional model of the middle atmosphere indicated that a relationship between gravitational separation and the age of air in the stratosphere would be significantly affected if the Brewer–Dobson circulation was enhanced due to global warming. Therefore, gravitational separation is usable as a new indicator of changes in the atmospheric circulation in the stratosphere

The objective of this research is to elucidate the seasonal and inter-annual variations of CO 2 exchanges between the atmosphere and a temperate deciduous forest in Japan and to elucidate their relation to meteorological conditions. The uptake rates of CO 2 from October 1993 to December 1996 were estimated from field measurements of CO 2 concentrations and meteorological conditions using a tower. Net of uptake rate of CO modeling of CO 2 and H 2 O fluxes over forests, Tellus 51B (1999), 2

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An average O2:CO2 exchange ratio for net turbulent O2 and CO2 fluxes in a cool temperate deciduous forest in central Japan was obtained based on an aerodynamic method using continuous measurements of atmospheric O2/N2 ratio and CO2 concentration. The average daily mean O2:CO2 exchange ratio was 0.86 during summer, 2013, a value significantly lower than the 1.1 used as a globally averaged terrestrial biospheric O2:CO2 exchange ratio in a CO2 budget analysis. Using the value of 0.86, along with the O2:CO2 exchange ratio of 1.11 for the ecosystem respiration (RE) and 1.00 for the gross primary production (GPP), the net ecosystem production (NEP) measured with an eddy covariance method was separated into GPP and RE using a one‐box canopy O2/CO2 budget model. The estimated average daily‐mean GPP and RE values were consistent, within estimation errors, with those estimated from an empirical function of air temperature; the RE values were also comparable to the soil CO2 efflux observed using an open‐flow soil chamber method. These results suggest that the simultaneous observation of O2 and CO2 concentrations in a forest has potential as a new tool to evaluate the forest CO2 budget.