Variability in the O2/N2 ratio of southern hemisphere air, 1991–1994: Implications for the carbon cycle

Bender, Michael L.; Ellis, Taylor; Tans, Pieter P.; Francey, R. J.; Lowe, David C.

doi:10.1029/95gb03295

Cited by 123 publications

(119 citation statements)

References 26 publications

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“…Measurements of variations in atmospheric oxygen have provided a wealth of insights into the global carbon cycle [Keeling and Shertz, 1992;Keeling et al, 1993Keeling et al, , 1996Bender et al, 1996;Battle et al, 2000]. This is because atmospheric oxygen is in many respects a mirror of atmospheric CO2, caused by the tight link between 02 and CO2 that occurs during the photosynthesis by land plants and the subsequent respiration and remineralization of terrestrial organic matter [Severinghaus, 1995].…”

Section: Introductionmentioning

confidence: 99%

Air‐sea flux of oxygen estimated from bulk data: Implications For the marine and atmospheric oxygen cycles

Gruber¹,

Gloor

Fan³

et al. 2001

Global Biogeochemical Cycles

105

170

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Abstract. We estimate the annual net air-sea fluxes of oxygen for 13 regions on the basis of a steady state inverse modeling technique that is independent of air-sea gas exchange parameterizations. The inverted data consist of the observed oceanic oxygen concentration after a correction has been applied to account for biological cycling. We find that the tropical oceans (13øS-13øN) emit •212 Tmol 02 yr -•, which is compensated by uptake of 148 Tmol yr -• in the Northern Hemisphere (>13øN) and by uptake of 65 Tmol yr -• in the Southern Hemisphere (<13øS). These results imply that the dominant feature of oxygen transport in the combined oceanatmosphere system is the existence of a closed circulation cell in each hemisphere. These two cells consist of 02 uptake by the ocean in the middle and high latitudes of both hemispheres and transport in the ocean toward the tropics, where 02 is lost to the atmosphere and transported in the atmosphere back toward the poles. We find an asymmetry in the two cells involving 02 uptake in the temperate regions of the Northern Hemisphere versus loss of 02 in the temperate regions of the Southern Hemisphere. There is an additional asymmetry between the Atlantic basin, which has a net southward transport at all latitudes north of 36øS, in agreement with independent transport estimates, versus the Indian and Pacific Oceans, which have a strong equatorward transport everywhere. We find that these inverse estimates are relatively insensitive to details in the inversion scheme but are sensitive to biases in the ocean general circulation model that provides the linkage between surface fluxes and ocean interior concentrations. Forward simulations of 02 in an atmospheric tracer transport model using our inversely estimated oxygen fluxes as a boundary condition agree reasonably well with observations of atmospheric potential oxygen (APe m 02 + ce2). Our results indicate that the north-south asymmetry in the strength of the two hemispheric cells coupled with a strong asymmetry in fossil fuel emissions can explain much of the observed interhemispheric gradient in APe. Therefore it might not be necessary to invoke the existence of a large southward interhemispheric transport of e2 in the ocean, such as proposed by Stephens et al. [1998]. However, we find that uncertainties in the modeled APe distribution stemming from seasonal atmospheric rectification effects and the limited APe data coverage prevent the currently available APe data from providing strong constraints on the magnitude of interhemispheric transport. Stephens et al. [1998] recently proposed a new tracer combination, atmospheric potential oxygen (APO • 02 + CO2), that removes the terrestrial influence from the atmospheric 02 signal, including most of the signal from the burning of fossil fuels. Variations in APO therefore reflect mainly the air-sea exchange of oxygen and, to a smaller degree, also the air-sea exchange of CO2, N2, and a residual signal from the burning of fossil fuels. Annual mean observations of APO from 10 station...

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Section: Introductionmentioning

confidence: 99%

Air‐sea flux of oxygen estimated from bulk data: Implications For the marine and atmospheric oxygen cycles

Gruber¹,

Gloor

Fan³

et al. 2001

Global Biogeochemical Cycles

105

170

View full text Add to dashboard Cite

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“…Temperature-induced solubility changes also enhance these seasonal O 2 fluxes. Thus, the observed seasonal cycle of APO can be used to evaluate the ocean productivity (Keeling and Shertz, 1992;Bender et al, 1996) and to validate the oceanic O 2 fluxes estimated by different approaches (Keeling et al, 1998b;Balkanski et al, 1999;Garcia and Keeling, 2001). In these studies, oceanic O 2 , CO 2 and N 2 fluxes were used to drive atmospheric transport models to simulate atmospheric APO changes.…”

Section: Introductionmentioning

confidence: 99%

ENSO-related variability in latitudinal distribution of annual mean atmospheric potential oxygen (APO) in the equatorial Western Pacific

Tohjima¹,

Terao²,

Mukai³

et al. 2015

Tellus B: Chemical and Physical Meteorology

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A B S T R A C TWe examined temporal variations in the latitudinal distribution of annual mean atmospheric potential oxygen (APO 0O 2 '1.1 )CO 2 ), a useful tracer for studying ocean biogeochemical processes. To compute APO, we used atmospheric CO 2 and O 2 concentrations from flask samples and in-situ measurements onboard commercial cargo ships sailing between Japan and Australia/New Zealand. Most of the observed latitudinal distributions of the annual mean APO for the years 2002Á2012 showed equatorial bulges, indicating tropical APO outgassing fluxes. However, the equatorial bulge was noticeably absent during the 2009/2010 El Nin˜o period, especially in the Southern Hemisphere. The temporal variation in the 25Á08S latitudinal APO gradient correlated significantly with the El Nin˜o/Southern Oscillation (ENSO); the equatorward APO gradients decreased (increased) during the El Nin˜o (La Nin˜a) period with a variability of about 90.1 per meg/degree. Simulated APO based on an atmospheric transport model driven by climatological/constant flux fields and reanalysis meteorological data reproduced the overall characteristic of the observed temporal variation in the APO gradients well, suggesting that the atmospheric transport contributed substantially to the observed interannual variation in the global APO distributions. However, the model simulation underestimated the variability in the APO gradients by about 25%, compared to the observations. These discrepancies suggest a possibility of the existence of additional APO flux variability in the tropical Pacific, enhancing the ENSO-related variability in the observed APO gradients.

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“…Observations have been carried out at ground-based stations (e.g., Bender et al, 1996;Tohjima et al, 2003;Manning and Keeling, 2006;Stephens et al, 2007), sea-based station (van der LaanLuijkx et al, 2010), on oceanographic research/commercial vessels (Tohjima et al, 2005;Battle et al, 2006;Thompson et al, 2007), and from aircraft (Langenfelds et al, 1999;Sturm et al, 2005a). Langenfelds et al (1999), from their measurements over Cape Grim, Australia, reported that the O 2 /N 2 ratio between 0 and 1 km altitude decreased secularly, showing a prominent seasonal cycle, in agreement with surface measurements at the same site.…”

Section: Introductionmentioning

confidence: 99%

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

Ishidoya

Aoki

Goto

et al. 2012

Tellus B: Chemical and Physical Meteorology

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A B S T R A C T Systematic measurements of the atmospheric O 2 /N 2 ratio have been made using aircraft and ground-based stations in Japan since 1999. The observed seasonal cycles of the O 2 /N 2 ratio and atmospheric potential oxygen (APO) vary almost in opposite phase to that of the CO 2 concentration at all altitudes, and their amplitudes and phases are generally reduced and delayed, respectively, with increasing altitude. Simulations of APO using two atmospheric transport models reproduce general features of the observed seasonal cycle, but both models fail to reproduce the phase at an altitude ranging from 8 km to the tropopause. By analysing the observed secular trends of APO and CO 2 concentration, and assuming a global net oceanic O 2 outgassing of 0.290.5 GtC yr(1 , we estimate global average terrestrial biospheric and oceanic CO 2 uptake for the period 2000Á2010 to be 1.090.8 and 2.590.7 GtC yr (1 , respectively.Keywords: O 2 /N 2 ratio over Japan, Atmospheric Potential Oxygen (APO), Simulation of APO in the free troposphere, Terrestrial biospheric CO 2 uptake, Oceanic CO 2 uptake

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Variability in the O₂/N₂ ratio of southern hemisphere air, 1991–1994: Implications for the carbon cycle

Cited by 123 publications

References 26 publications

Air‐sea flux of oxygen estimated from bulk data: Implications For the marine and atmospheric oxygen cycles

Air‐sea flux of oxygen estimated from bulk data: Implications For the marine and atmospheric oxygen cycles

ENSO-related variability in latitudinal distribution of annual mean atmospheric potential oxygen (APO) in the equatorial Western Pacific

Time and space variations of the O<sub>2</sub>/N<sub>2</sub> ratio in the troposphere over Japan and estimation of the global CO<sub>2</sub> budget for the period 2000–2010

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