1. Evaluation of the Airborne Quantum Cascade Laser Spectrometer (QCLS) measurements of the carbon and greenhouse gas suite - CO2, CH4, N2O, and CO - during the CalNex and HIPPO campaigns.
- Author
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Santoni, G. W., Daube, B. C., Kort, E. A., Jiménez, R., Park, S., Pittman, J. V., Gottlieb, E., B. Xiang, Zahniser, M. S., Nelson, D. D., McManus, J. B., Peischl, J., Ryerson, T. B., Holloway, J. S., Andrews, A. E., Sweeney, C., Hall, B. D., Hintsa, E. J., Moore, F. L., and Elkins, J. W.
- Subjects
GREENHOUSE gases ,CARBON compounds ,QUANTUM cascade lasers ,FAR ultraviolet radiation ,INFRARED spectroscopy equipment ,MOLE fraction - Abstract
We present an evaluation of aircraft observations of the carbon and greenhouse gases (CO
2 , CH4 , N2 O, and CO) using a direct-absorption pulsed quantum cascade laser spectrometer (QCLS) operated during the HIPPO and CalNex airborne experiments. The QCLS made continuous 1Hz measurements with 1-sigma Allan precisions of2 0, 0.5, 0.09, and 0.15 ppb for CO2 , CH4 , N2 O, and CO, respectively, over >500 flight hours on 79 research flights. The QCLS measurements are compared to two vacuum ultraviolet (VUV) CO instruments (CalNex and HIPPO), a cavity ring-down spectrometer (CRDS) measuring CO2 and CH4 (CalNex), two broadband non-dispersive infrared spectrometers (NDIR) measuring CO2 (HIPPO), two onboard gas chromatographs measuring a variety of chemical species including CH4 , N2 O, and CO (HIPPO), and various flask-based measurements of all four species. QCLS measurements are tied to NOAA and WMO standards using an in-flight calibration system and mean differences when compared to NOAA CCG flask data over the 59 HIPPO research flights were 100, 1, 1, and2 ppb for CO2 , CH4 , N2 O, and CO, respectively. The details of the end-to-end calibration procedures and the data quality-assurance and quality-control (QA/QC) are presented. Specifically, we discuss our practices for the traceability of standards given uncertainties in calibration cylinders, isotopic and surface effects for the long-lived greenhouse gas tracers, interpolation techniques for in-flight calibrations, and the effects of instrument linearity on retrieved mole fractions. [ABSTRACT FROM AUTHOR]- Published
- 2013
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