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Atmospheric Measurement Techniques An interactive open-access journal of the European Geosciences Union
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Volume 11, issue 11
Atmos. Meas. Tech., 11, 6059-6074, 2018
https://doi.org/10.5194/amt-11-6059-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Atmos. Meas. Tech., 11, 6059-6074, 2018
https://doi.org/10.5194/amt-11-6059-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 09 Nov 2018

Research article | 09 Nov 2018

Testing and evaluation of a new airborne system for continuous N2O, CO2, CO, and H2O measurements: the Frequent Calibration High-performance Airborne Observation System (FCHAOS)

Alexander Gvakharia1, Eric A. Kort1, Mackenzie L. Smith1,2, and Stephen Conley2 Alexander Gvakharia et al.
  • 1Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, Michigan, USA
  • 2Scientific Aviation, Boulder, Colorado, USA

Abstract. We present the development and assessment of a new flight system that uses a commercially available continuous-wave, tunable infrared laser direct absorption spectrometer to measure N2O, CO2, CO, and H2O. When the commercial system is operated in an off-the-shelf manner, we find a clear cabin pressure–altitude dependency for N2O, CO2, and CO. The characteristics of this artifact make it difficult to reconcile with conventional calibration methods. We present a novel procedure that extends upon traditional calibration approaches in a high-flow system with high-frequency, short-duration sampling of a known calibration gas of near-ambient concentration. This approach corrects for cabin pressure dependency as well as other sources of drift in the analyzer while maintaining a  ∼ 90% duty cycle for 1Hz sampling. Assessment and validation of the flight system with both extensive in-flight calibrations and comparisons with other flight-proven sensors demonstrate the validity of this method. In-flight 1σ precision is estimated at 0.05ppb, 0.10ppm, 1.00ppb, and 10ppm for N2O, CO2, CO, and H2O respectively, and traceability to World Meteorological Organization (WMO) standards (1σ) is 0.28ppb, 0.33ppm, and 1.92ppb for N2O, CO2, and CO. We show the system is capable of precise, accurate 1Hz airborne observations of N2O, CO2, CO, and H2O and highlight flight data, illustrating the value of this analyzer for studying N2O emissions on  ∼ 100km spatial scales.

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We present a new flight system to measure the atmospheric trace gases N2O, CO2, CO, and H2O. We use a novel calibration technique to correct altitude-dependent artifacts that have hindered similar instruments. In-flight null-tests and comparison with other flight-proven instruments provide validation. This high-precision, high-accuracy system provides opportunities for airborne studies to improve our understanding of N2O emission processes.
We present a new flight system to measure the atmospheric trace gases N2O, CO2, CO, and H2O. We...
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