Time and space variations of the O₂/N₂ ratio in the troposphere over Japan and estimation of the global CO₂ budget for the period 2000–2010

Figures & data

Fig. 1.  δ(O₂/N₂) of 6 standard air samples determined against the primary standard air. Open and closed circles represent the results obtained when the cylinders are standing up and lying down on the floor, respectively.

Fig. 2.  δ(O₂/N₂) and CO₂ concentration observed in the troposphere over Japan and at the ground surface in the suburbs of Sendai, Japan.

Fig. 3.  Average seasonal cycles of δ(O₂/N₂), CO₂ concentration and APO observed in the troposphere over Japan and at the surface in Sendai (a–c), and average seasonal APO cycles calculated using STAG (solid lines) and ACTM (dashed lines) for the corresponding altitudes (d).

Fig. 6.  Peak-to-peak amplitudes and appearance times of the maxima and minima of the average seasonal APO cycles observed at (a) Northern Hemispheric coastal sites and (b) high-altitude and inland sites. The results obtained using STAG and ACTM are also shown.

Fig. 4.  Five-d backward trajectories calculated using HYSPLIT for our observation dates in 2005, 2006 and 2007. Red, black, blue and green lines indicate trajectories from the surface in Sendai, 2, 4 km and 8 km-tropopause over Japan, respectively.

Fig. 5.  (a) Fractions of the seasonal CO₂ concentration, δ(O₂/N₂) and APO amplitudes at the respective altitudes to the surface, and (b) appearance times of the maxima and minima of the average seasonal cycles of CO₂ concentration and APO observed in the troposphere over Japan and at the surface in the suburbs of Sendai. Also shown in (b) are the results obtained using STAG and ACTM for APO.

Table 1. Oceanic and terrestrial biosphere CO₂ uptake estimated from the present and other recent studies based on atmospheric O₂ and CO₂ measurements

Time period	Data	Ocean sink (GtC yr^−1)	Land sink (GtC yr^−1)
This study 2000–2010	Sendai and over Japan	2.5±0.7	1.1±0.8
Tohjima et al. (2008)	Hateruma, Cape Ochi-ishi	2.1±0.7	1.0±0.9
July 1999–July 2005
Bender et al. (2005)	Cape Grim	1.8±0.5	1.1±0.6
June 1993–June 2002		(2.3±0.5)^a	(0.6±0.6)
Manning and Keeling (2006)	Alert, La Jolla, Cape Grim	2.2±0.6	0.5±0.7
January 1993–January 2003		(2.2±0.6)	(0.6±0.7)
Van der Laan-Luikx et al. (2010) 1998–2009	Mace Head	1.8±0.8

^aThe values in brackets are recalculated values by Tohjima et al. (2008) using the updated data of global CO₂ changes from the NOAA/ESRL/GMD and fossil fuel CO₂ emissions, and the net oceanic O₂ outgassing of 0.48±0.48 GtC yr⁻¹.

Fig. 7.  Terrestrial biospheric and oceanic CO₂ uptake estimated by the present and other studies for the period after 1960.

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