Testing and evaluation of a new airborne system for continuous N<sub>2</sub>O, CO<sub>2</sub>, CO, and H<sub>2</sub>O measurements: the Frequent Calibration High-performance Airborne Observation System (FCHAOS)
<p>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 N<sub>2</sub>O, CO<sub>2</sub>, CO, and H<sub>2</sub>O. When the comme...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-11-01
|
| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://www.atmos-meas-tech.net/11/6059/2018/amt-11-6059-2018.pdf |
| Summary: | <p>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 N<sub>2</sub>O, CO<sub>2</sub>, CO, and
H<sub>2</sub>O. When the commercial system is operated in an off-the-shelf
manner, we find a clear cabin pressure–altitude dependency for
N<sub>2</sub>O, CO<sub>2</sub>, 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 1 Hz 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 1<i>σ</i> precision is estimated at
0.05 ppb, 0.10 ppm, 1.00 ppb, and 10 ppm for N<sub>2</sub>O,
CO<sub>2</sub>, CO, and H<sub>2</sub>O respectively, and traceability to World
Meteorological Organization (WMO) standards (1<i>σ</i>) is 0.28 ppb,
0.33 ppm, and 1.92 ppb for N<sub>2</sub>O, CO<sub>2</sub>, and CO. We show
the system is capable of precise, accurate 1 Hz airborne observations of
N<sub>2</sub>O, CO<sub>2</sub>, CO, and H<sub>2</sub>O and highlight flight
data, illustrating the value of this analyzer for studying N<sub>2</sub>O
emissions on ∼ 100 km spatial scales.</p> |
|---|---|
| ISSN: | 1867-1381 1867-8548 |