Measurements of the Carbon Dioxide Flux over the Ocean

Ohtaki, Eiji; Tsukamoto, Osamu; Iwatani, Yoshiharu; Mitsuta, Yasushi

doi:10.2151/jmsj1965.67.4_541

Cited by 14 publications

(10 citation statements)

References 17 publications

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“…Apparently, the CO 2 density fluctuation showed the contrary behaviour from the CO 2 mixing ratio under the significant influence of air temperature and H 2 O density fluctuations. Thus, in the present study, the total CO 2 flux by the OPEC changed sign due to the WPL correction, which is similar to the results given by previous studies (Ohtaki et al, 1989;Kondo and Tsukamoto, 2007).…”

Section: Atmospheric Turbulent Fluctuationssupporting

confidence: 92%

Comparative CO<sub>2</sub> flux measurements by eddy covariance technique using open- and closed-path gas analysers over the equatorial Pacific Ocean

Kondo

Tsukamoto

2012

Tellus B: Chemical and Physical Meteorology

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Direct comparison of airÁsea CO 2 fluxes by open-path eddy covariance (OPEC) and closed-path eddy covariance (CPEC) techniques was carried out over the equatorial Pacific Ocean. Previous studies over oceans have shown that the CO 2 flux by OPEC was larger than the bulk CO 2 flux using the gas transfer velocity estimated by the mass balance technique, while the CO 2 flux by CPEC agreed with the bulk CO 2 flux. We investigated a traditional conflict between the CO 2 flux by the eddy covariance technique and the bulk CO 2 flux, and whether the CO 2 fluctuation attenuated using the closed-path analyser can be measured with sufficient time responses to resolve small CO 2 flux over oceans. Our results showed that the closed-path analyser using a short sampling tube and a high volume air pump can be used to measure the small CO 2 fluctuation over the ocean. Further, the underestimated CO 2 flux by CPEC due to the attenuated fluctuation can be corrected by the bandpass covariance method; its contribution was almost identical to that of H 2 O flux. The CO 2 flux by CPEC agreed with the total CO 2 flux by OPEC with density correction; however, both of them are one order of magnitude larger than the bulk CO 2 flux.

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Section: Atmospheric Turbulent Fluctuationssupporting

confidence: 92%

Comparative CO<sub>2</sub> flux measurements by eddy covariance technique using open- and closed-path gas analysers over the equatorial Pacific Ocean

Kondo

Tsukamoto

2012

Tellus B: Chemical and Physical Meteorology

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“…The general features of the fluxes derived by the three methods agreed well and the absolute values of those fluxes were positively correlated with U. Table 3 Ohtaki et al (1989) reported upward efflux at the same site as Iwata et al (2004) contributions dominated in estimating F C,EC and F C,VA and were positively correlated with U (Figs. 13b, c, e, and f ).…”

Section: Comparison Of Fluxes Derived By the Three Methodsmentioning

confidence: 61%

“…λE, and net gain G, in previous studies and in this study. Results from Kondo (1976) were obtained from his Table A1; results from Ohtaki et al (1989) were averaged from their Table 2; results from Ishii and Kondo (1993) were from their Figure 10c; results from and were from their …”

Section: Energy Budgets Over the Sea Surfacementioning

confidence: 99%

Turbulent Flux Observations at the Tip of a Narrow Cape on Miyako Island in Japan's Southwestern Islands

Tanaka

Hiyama

Nakamura

2008

Journal of the Meteorological Society of Japan

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Air-sea fluxes were observed to elucidate the lower boundary conditions in the development of an atmospheric boundary layer over sea from 14 to 27 August 2002. Fluxes were observed at the tip of a narrow cape on Miyako Island, in Japan's Southwestern Islands. Flux measurements and turbulence properties were clearly divided by fetch condition or wind direction. Analysis of the footprint area and homogeneity indicated that air-sea fluxes over an upwind sea surface were observed in cases of approximately 30% for all observation periods. The bulk transfer (BT), eddy covariance (EC), and variance (VA) methods were used to evaluate air-sea fluxes. The general features of the estimated fluxes were similar. Averaged sensible heat flux of approximately 6 W m −2 was obtained by all three methods, and the latent heat fluxes were 92, 60, and 71 W m −2 by the BT, EC, and VA methods, respectively. Daily mean net radiation input R NET was 223 W m −2 . The sea surface was a large energy sink during the observation period.

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“…Practically, sensible and latent heat fluxes evaluated by the eddy covariance technique are used to calculate water vapor and CO2 fluxes by the mean vertical flow (Webb or WPL correction). Ohtaki et al (1989) suggested that the Webb CO2 flux due to air density fluctuation is larger than the raw CO2 flux and changes the transport direction of the total CO2 flux over the coastal sea surface. Kondo and Tsukamoto (2007) also confirmed these results over the open ocean surface.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Webb Correction on CO2 Flux by Eddy Covariance Technique Using Open-Path Gas Analyzer over Asphalt Surface

Kondo¹,

Tsukamoto²

2008

J. Agric. Meteorol.

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Webb correction is indispensable when evaluating trace gas flux by the eddy covariance technique using an open-path gas analyzer. In the present study, direct measurements of CO2 flux by the eddy covariance technique using an open-path CO2/H2O gas analyzer were carried out over an asphalt surface where CO2 and latent heat fluxes were considered almost zero. The power spectrum of CO2 density fluctuation had similar frequency structure to those of vertical wind velocity, sound virtual temperature, and water vapor density fluctuations. The cospectrum of raw CO2 flux was negatively correlated with that of sensible heat flux. The cospectrum of latent heat flux was almost zero and poorly correlated with that of raw CO2 or sensible heat fluxes. Raw CO2 flux was apparently downward from the atmosphere to the asphalt surface during this observation period. The Webb CO2 correction term for sensible heat flux was upward and larger than the raw CO2 flux, although the Webb CO2 correction term for latent heat flux was almost zero. Total latent heat and CO2 fluxes were evaluated as significant upward fluxes. This result shows that Webb correction may cause an overestimated correction to CO2 flux by the eddy covariance technique using an open-path CO2/H2O gas analyzer over surfaces, especially where small CO2 flux by soil respiration or air-sea exchange process is observed.

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Measurements of the Carbon Dioxide Flux over the Ocean

Abstract: Atmospheric fluctuations of carbon dioxide, humidity and temperature were simultaneously measured over the ocean,

Cited by 14 publications

References 17 publications

Comparative CO<sub>2</sub> flux measurements by eddy covariance technique using open- and closed-path gas analysers over the equatorial Pacific Ocean

Comparative CO<sub>2</sub> flux measurements by eddy covariance technique using open- and closed-path gas analysers over the equatorial Pacific Ocean

Turbulent Flux Observations at the Tip of a Narrow Cape on Miyako Island in Japan's Southwestern Islands

Evaluation of Webb Correction on CO2 Flux by Eddy Covariance Technique Using Open-Path Gas Analyzer over Asphalt Surface

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