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. Author manuscript; available in PMC: 2020 Oct 29.
Published in final edited form as: Earth Syst Sci Data. 2020;12(1):https://doi.org/10.5194/essd-12-699-2020.

Figure 5.

Figure 5.

Time series of standard tank run residuals (i.e., XDC−C) for CO2 (a, b), CH4 (c, d), and CO (e, f). XDC is calculated using a single calibration tank (not shown) and the ratio method (Eq. 2) on the left (a, c, e) and the difference method (Eq. 3) on the right (b, d, f). Assigned tank values are shown in the legend; one tank was not calibrated for CO so only the residuals of the high-concentration tank at 315 nmol mol−1 are shown. The residual magnitude is smaller for CO2 and CH4 using the ratio method, but the standard deviations (variability) are similar using both methods. For CO, both the magnitude of the residual and the standard deviation are smaller using the difference equation; the ratio equation does not properly account for the drift in the analyzer at the start of the time series (May–June). Data shown are from MSH; a measurement gap exists in July.