| Autor: |
Vogel, F. R., Huang, L., Ernst, D., Giroux, L., Racki, S., Worthy, D. E. J. |
| Předmět: |
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| Zdroj: |
Atmospheric Measurement Techniques; 2013, Vol. 6 Issue 2, p301-308, 8p, 1 Diagram, 2 Charts, 5 Graphs |
| Abstrakt: |
With the emergence of wide-spread application of new optical techniques to monitor δ13C in atmospheric CO2 there is a growing need to ensure well-calibrated measurements. We characterized one commonly available instrument, a cavity ring-down spectrometer (CRDS) system used for continuous in situ monitoring of atmospheric 13CO2. We found no dependency of δ13C on the CO2 concentration in the range of 303-437 ppm. We designed a calibration scheme according to the diagnosed instrumental drifts and established a quality assurance protocol. We find that the repeatability (1-σ) of measurements is 0.25 ‰ for 10 min and 0.15 ‰ for 20 min integrated averages, respectively. Due to a spectral overlap, our instrument displays a cross-sensitivity to CH4 of 0.42±0.024 ‰ ppm-1. Our ongoing target measurements yield standard deviations of δ13C from 0.22 ‰ to 0.28 ‰ for 10 min averages. We furthermore estimate the reproducibility of our system for ambient air samples from weekly measurements of a long-term target gas to be 0.18 ‰. We find only a minuscule offset of 0.002±0.025 ‰ between the CRDS and Environment Canada's isotope ratio mass spectrometer (IRMS) results for four target gases used over the course of one year. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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