@article{oai:nipr.repo.nii.ac.jp:00003752,
 author = {ナカザワ, タカキヨ and モリモト, シンジ and アオキ, シュンジ and タナカ, マサユキ and NAKAZAWA, Takakiyo and MORIMOTO, Shinji and AOKI, Shuhji and TANAKA, Masayuki},
 journal = {Proceedings of the NIPR Symposium on Polar Meteorology and Glaciology},
 month = {Dec},
 note = {P(論文), Carbon dioxide samples collected in the troposphere over Japan during the periods from April 1984 to November 1990 were analyzed for the carbon isotope ratio, δ^<13>C, with a precision of 0.03‰ (one standard deviation). The seasonal cycle of δ^<13>C decreased with increasing height, with a phase delay of about one month between the lower and upper troposphere, which was quite similar to that of the CO_2 concentration. It was found from the observed seasonal cycles of the CO_2 concentration and δ^<13>C that the rate of change in δ^<13>C with respect to the CO_2 concentration is about -0.05‰ per ppmv. This implies that the seasonal CO_2 cycle over Japan is mainly induced by seasonally dependent biospheric activities. However, the air transport from different latitudes is also important for the seasonal CO_2 cycle, especially in the upper troposphere. δ^<13>C decreased secularly at an average rate of about -0.03‰ per year due mainly to combustion of fossil fuels with lighter CO_2 relative to the atmospheric CO_2. Irregular variations of δ^<13>C with the periods of two or three years, superimposed on the secular trend, were also observed; they were almost in phase with these of the CO_2 concentration. From the comparison of both irregular variations, it was found that the cause could primarily attributed to the imbalance in CO_2 exchange between the atmosphere and biosphere in association with climate change, rather than between the atmosphere and oceans.},
 title = {VARIATIONS OF CARBON ISOTOPIC RATIO OF ATMOSPHERIC CARBON DIOXIDE OVER JAPAN},
 volume = {6},
 year = {1992}
}