Development of a new high precision continuous measuring system for atmospheric O₂/N₂ and Ar/N₂ and its application to the observation in Tsukuba, Japan

Abstract

A B S T R A C TA high precision continuous measurement system has been developed for analysis of the atmospheric O 2 /N 2 and Ar/N 2 ratios based on a mass spectrometry method. Sample and reference air flows through an inlet system and only a miniscule amount of each is transferred to the ion source of the mass spectrometer through thermally insulated thin fused silica capillaries. The measured O 2 /N 2 and Ar/N 2 values are experimentally corrected for the effects of pressure imbalance between the sample air and reference air during their introduction into the mass spectrometer, as well as for the influence of CO 2 concentration and O 2 /N 2 ratio of the sample air. Standard deviations of the measured O 2 /N 2 and Ar/N 2 ratios of standard air are 93.2 and 96.5 per meg, respectively, for our normal measurement time of 62 seconds. Our standard air is prepared by drying natural air and then stored in 48-L high-pressure cylinders; its O 2 /N 2 and Ar/N 2 ratios are stable to within 91.1 and 95.8 per meg, respectively, over a period of 11 months. The CO 2 /N 2 ratio is also simultaneously measured by this system, and converted to CO 2 concentration with a precision better than 90.3 ppm using an experimentally determined relationship. This system has been field tested in Tsukuba, Japan since February 2012. Preliminary results show clear seasonal cycles of atmospheric potential oxygen (APO 0O 2 '1.1)CO 2 ), as well as of Ar/N 2 . If we ignore the fossil fuel influence, then that part the seasonal APO cycle driven by the airÁsea heat flux accounts for 23% of the observed seasonal APO cycle, as estimated from the seasonal cycle of Ar/N 2 ; any residuals are attributed to ocean biology and ventilation.

New Atmospheric O₂/N₂ Ratio Measurements over the Western North Pacific Using a Cargo Aircraft C-130H

“…Bender et al 1994). In addition, the measured (Ar/N 2 ) variability of about 800 per meg is also outside the natural range since its small seasonal cycle at the surface driven by the thermally-driven air-sea Ar and N 2 fluxes has a peak-to-peak amplitude of only 10−35 per meg (Keeling et al 2004;Cassar et al 2008;Ishidoya and Murayama 2014). It is suggested therefore, that the significant variations of the measured (Ar/N 2 ),  15 N and …”

“…The maximum correction is found to be about 200 per meg. It should also be noted that (Ar/N 2 ) shows a small seasonal cycle at the surface around Japan, with a peak-to-peak amplitude of about 16 per meg at Tsukuba (Ishidoya and Murayama 2014). The effect of the seasonal (Ar/N 2 ) cycle on the (O 2 /N 2 ) cor.…”

“…Therefore, we use the annual average value of (Ar/N 2 ) observed at the surface in Tsukuba (36°N, 140°E), Japan (Ishidoya and Murayama 2014) as the reference point in calculating D(Ar/N 2 ) meas. .…”

Age and gravitational separation of the stratospheric air over Indonesia

“…The technical details of our mass spectrometry analyses have been described in Ishidoya and Murayama (2014). In this study, only the method of sample air flow into the mass spectrometer was modified from the previous method described in Ishidoya et al (2013).…”

Development of a Continuous Measurement System for Atmospheric O₂/N₂ Ratio Using a Paramagnetic Analyzer and Its Application in Minamitorishima Island, Japan

“…For comparison between the system developed in this study and mass spectrometer (Ishidoya and Murayama 2014), we performed simultaneous measurements using the both methods. Figure 4a shows the values of δ(O 2 /N 2 ) and CO 2 concentration obtained by the present measurement system (Fig.…”