Ship-based observations of atmospheric potential oxygen and regional air–sea O₂ flux in the northern North Pacific and the Arctic Ocean

Figures & data

Fig. 1 Locations where air samples were collected (small stars) onboard MIRAI for the period 5 September–15 October 2012 (red) 29 August–6 October 2013 (blue), and 1 September–9 October 2014 (green). Locations of Ny-Ålesund Station, Svalbard, Norway, and Sendai, Japan, are also shown (large purple stars).

Fig. 2 Temporal variations in δ(O₂/N₂), CO₂ concentration and δ¹³C of CO₂ observed onboard MIRAI for the period 5 September–15 October 2012 (black filled circles). Temporal variation in CO concentration (grey crosses), latitude and longitude of the cruise are also shown.

Fig. 3 Same as in Fig. 2 but for the period 29 August–6 October 2013.

Fig. 4 Same as in Fig. 2 but for the period 1 September–9 October 2014.

Fig. 5 Relationships of (a) δ(O₂/N₂) and (b) δ¹³C of CO₂ with CO₂ concentration observed onboard MIRAI for the period 5 September–15 October 2012, 29 August–6 October 2013, and 1 September–9 October 2014.

Fig. 6 Temporal variations in APO (filled black circles) and air–sea O₂ flux observed onboard MIRAI (F_{O2_obs}; green dots, positive value denotes flux emitted from the ocean to the atmosphere) for the period 5 September–15 October 2012. Corresponding APO values simulated using the STAG model that incorporated the monthly air–sea O₂ (N₂) flux climatology (blue crosses), and the climatological air–sea O₂ flux along the observation route (F_{O2_cli}; blue dots) are also plotted. Simulated APO values calculated by including the contribution of air–sea CO₂ flux are also shown by the blue dotted line (see text). Green crosses denote temporal variations in APO calculated by using F_{O2_obs} (see text). Chlorophyll-a concentration, partial pressure of O₂ and CO₂ in surface water, heights of planetary boundary layer (PBLH), wind speed at 25-m heights, latitude and longitude of the cruise are also shown.

Fig. 7 Same as in Fig. 6 but for the 29 August–6 October 2013.

Fig. 8 Same as in Fig. 6 but for the period 1 September–9 October 2014.

Fig. 9 Seasonal components of the observed APO (grey dots) and the simulated APO (blue dots) by STAG model incorporated with F_{O2_cli} and F_{N2_cli} at (a) Ny-Ålesund, Svalbard, for the period 2001–2010 (Ishidoya et al., 2012a) and (b) Sendai, Japan, for the period 1999–2009 (Ishidoya et al., 2012b). Best-fitted curves to the observed and simulated data consisting of two-harmonics are also shown by black and blue solid lines, respectively. Blue dashed lines denote the same best-fitted curves to the simulated data but for including the contribution of air–sea CO₂ flux. Green dashed lines denote the APO values calculated as a sum of the simulated APO and changes in APO expected from a uniform mixing of the sea-to-air O₂ fluxes, emitted from the northern hemispheric ocean at a uniform rate of 0.3 µmol·m⁻²·s⁻¹ for the period from mid-September to the end of November. Green dashed-dot-dot lines denote the best-fitted curves to the simulated APO produced by the adjusted F_{O2_cli} values. See text for details.

Ishidoya S., Morimoto S., Aoki S., Taguchi S., Goto D., co-authors. Oceanic and terrestrial biospheric CO2 uptake estimated from atmospheric potential oxygen observed at Ny-Alesund, Svalbard, and Syowa, Antarctica. Tellus B. 2012a; 64: 18924. DOI: http://dx.doi.org/10.3402/tellusb.v64i0.18924.

 Google Scholar

Ishidoya S., Aoki S., Goto D., Nakazawa T., Taguchi S., co-authors. Time and space variations of the O2/N2 ratio in the troposphere over Japan and estimation of global CO2 budget. Tellus B. 2012b; 64: 18964. DOI: http://dx.doi.org/10.3402/tellusb.v64i0.18964.

 Google Scholar