15:30 〜 15:45
[AAS12-07] スヴァールバル諸島ニーオルスンにおける大気中CO2濃度および炭素同位体比の時間変動
キーワード：二酸化炭素、炭素同位体比、酸素/窒素比
Long-term measurements of the atmospheric CO2 concentration and its carbon isotope ratio (d13C) have been used for partitioning CO2 sinks into the terrestrial biosphere and the ocean. However, the CO2 sinks estimated from d13C suffer with uncertainties in isotopic disequilibrium flux between the atmosphere and the ocean and between the atmosphere and the terrestrial biosphere (so-called isoflux). For a better understanding of the global carbon cycle, we have been carrying out the systematic observation of the atmospheric CO2 concentration and d13C at Ny-Ålesund (78.93°N, 11.83°E), Svalbard since 1991 by weekly air sampling with subsequent analysis in NIPR. Here, we will present the observational results of CO2 concentration and d13C for 1991–2013 and 1996–2013, respectively. The d13C data before 1996 were removed from our analysis due to experimental and sample quality problems (Morimoto et al., 2001).
The CO2 concentrations show a clear seasonal cycle with peak-to-peak amplitude of about 17 ppmv, which reaches the maxima in late April to early May and the minima in late August, superimposed on a secular increase with an average rate of 2.0 ppmv/yr for the period of 1996–2013. On the other hand, the d13C decreases secularly at an average rate of –0.018 ‰/yr, and varies seasonally in opposite phase with the CO2 concentration. We have also maintained atmospheric d(O2/N2) measurements at Ny-Ålesund since 2001 (Ishidoya et al., 2012). Using the atmospheric d(O2/N2) and CO2 concentration records, the terrestrial and oceanic CO2 sinks are estimated to be 1.7 ± 0.8 GtC/yr and 2.2 ± 0.7 GtC/yr, respectively, for the 13-year period (2001–2013). Using these values of CO2 sinks and the d13C record, the average isofulx for the period of 2001–2013 is estimated to be 99 ± 28 Gt ‰/yr.
References
Ishidoya et al. (2012) Oceanic and terrestrial biospheric CO2 uptake estimated from atmospheric potential oxygen observed at Ny-Ålesund, Svalbard and Syowa, Antarctica. Tellus B, 64, 18924, http://dx.doi.org/10.3402/tellusb.v64i0.18924.
Morimoto et al. (2001) Temporal variations of atmospheric CO2 concentration and carbon isotope ratio in Ny-Alesund, Svalbard, Mem. Natl Inst. Polar Res., Spec. Issue, 54, 71–79.
The CO2 concentrations show a clear seasonal cycle with peak-to-peak amplitude of about 17 ppmv, which reaches the maxima in late April to early May and the minima in late August, superimposed on a secular increase with an average rate of 2.0 ppmv/yr for the period of 1996–2013. On the other hand, the d13C decreases secularly at an average rate of –0.018 ‰/yr, and varies seasonally in opposite phase with the CO2 concentration. We have also maintained atmospheric d(O2/N2) measurements at Ny-Ålesund since 2001 (Ishidoya et al., 2012). Using the atmospheric d(O2/N2) and CO2 concentration records, the terrestrial and oceanic CO2 sinks are estimated to be 1.7 ± 0.8 GtC/yr and 2.2 ± 0.7 GtC/yr, respectively, for the 13-year period (2001–2013). Using these values of CO2 sinks and the d13C record, the average isofulx for the period of 2001–2013 is estimated to be 99 ± 28 Gt ‰/yr.
References
Ishidoya et al. (2012) Oceanic and terrestrial biospheric CO2 uptake estimated from atmospheric potential oxygen observed at Ny-Ålesund, Svalbard and Syowa, Antarctica. Tellus B, 64, 18924, http://dx.doi.org/10.3402/tellusb.v64i0.18924.
Morimoto et al. (2001) Temporal variations of atmospheric CO2 concentration and carbon isotope ratio in Ny-Alesund, Svalbard, Mem. Natl Inst. Polar Res., Spec. Issue, 54, 71–79.