A lightweight broadband cavity-enhanced spectrometer for NO<sub>2</sub> measurement on uncrewed aerial vehicles

<p>We describe the design and performance of a lightweight broadband cavity-enhanced spectrometer for measurement of NO<span class="inline-formula"><sub>2</sub></span> on uncrewed aerial vehicles and light aircraft. The instrument uses a light-emitting diode (...

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Main Authors: C. C. Womack, S. S. Brown, S. J. Ciciora, R.-S. Gao, R. J. McLaughlin, M. A. Robinson, Y. Rudich, R. A. Washenfelder
Format: Article
Language:English
Published: Copernicus Publications 2022-11-01
Series:Atmospheric Measurement Techniques
Online Access:https://amt.copernicus.org/articles/15/6643/2022/amt-15-6643-2022.pdf
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author C. C. Womack
C. C. Womack
S. S. Brown
S. S. Brown
S. J. Ciciora
R.-S. Gao
R. J. McLaughlin
M. A. Robinson
M. A. Robinson
Y. Rudich
R. A. Washenfelder
author_facet C. C. Womack
C. C. Womack
S. S. Brown
S. S. Brown
S. J. Ciciora
R.-S. Gao
R. J. McLaughlin
M. A. Robinson
M. A. Robinson
Y. Rudich
R. A. Washenfelder
author_sort C. C. Womack
collection DOAJ
description <p>We describe the design and performance of a lightweight broadband cavity-enhanced spectrometer for measurement of NO<span class="inline-formula"><sub>2</sub></span> on uncrewed aerial vehicles and light aircraft. The instrument uses a light-emitting diode (LED) centered at 457 nm, high-finesse mirrors (reflectivity <span class="inline-formula">=0.999963</span> at 450 nm), and a grating spectrometer to determine optical extinction coefficients between 430 and 476 nm, which are fit with custom spectral fitting software and published absorption cross sections. The instrument weighs 3.05 kg and has a power consumption of less than 35 W at 25 <span class="inline-formula"><sup>∘</sup></span>C. A ground calibration unit provides helium and zero air flows to periodically determine the reflectivity of the cavity mirrors using known Rayleigh scattering cross sections. The precision (1<span class="inline-formula"><i>σ</i></span>) for laboratory measurements is 43 ppt NO<span class="inline-formula"><sub>2</sub></span> in 1 s and 7 ppt NO<span class="inline-formula"><sub>2</sub></span> in 30 s. Measurement of air with known NO<span class="inline-formula"><sub>2</sub></span> mixing ratios in the range of 0–70 ppb agreed with the known values within 0.3 % (slope <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M9" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>=</mo><mn mathvariant="normal">0.997</mn><mo>±</mo><mn mathvariant="normal">0.007</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="78pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="070c85d9bb34c1e2574f428ab72c4964"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="amt-15-6643-2022-ie00001.svg" width="78pt" height="10pt" src="amt-15-6643-2022-ie00001.png"/></svg:svg></span></span>; <span class="inline-formula"><i>r</i><sup>2</sup>=0.99983</span>). We demonstrate instrument performance using vertical profiles of the NO<span class="inline-formula"><sub>2</sub></span> mixing ratio acquired on board an uncrewed aerial vehicle between 0 and 110 m above ground level in Boulder, Colorado.</p>
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spelling doaj.art-2c97a8d078ed45b1a54ce7748b21ab952022-12-22T04:15:03ZengCopernicus PublicationsAtmospheric Measurement Techniques1867-13811867-85482022-11-01156643665210.5194/amt-15-6643-2022A lightweight broadband cavity-enhanced spectrometer for NO<sub>2</sub> measurement on uncrewed aerial vehiclesC. C. Womack0C. C. Womack1S. S. Brown2S. S. Brown3S. J. Ciciora4R.-S. Gao5R. J. McLaughlin6M. A. Robinson7M. A. Robinson8Y. Rudich9R. A. Washenfelder10Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, USAChemical Sciences Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, USAChemical Sciences Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, USADepartment of Chemistry, University of Colorado, Boulder, CO 80309, USAChemical Sciences Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, USAChemical Sciences Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, USAChemical Sciences Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, USACooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, USAChemical Sciences Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, USADepartment of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot 7610001, IsraelChemical Sciences Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, USA<p>We describe the design and performance of a lightweight broadband cavity-enhanced spectrometer for measurement of NO<span class="inline-formula"><sub>2</sub></span> on uncrewed aerial vehicles and light aircraft. The instrument uses a light-emitting diode (LED) centered at 457 nm, high-finesse mirrors (reflectivity <span class="inline-formula">=0.999963</span> at 450 nm), and a grating spectrometer to determine optical extinction coefficients between 430 and 476 nm, which are fit with custom spectral fitting software and published absorption cross sections. The instrument weighs 3.05 kg and has a power consumption of less than 35 W at 25 <span class="inline-formula"><sup>∘</sup></span>C. A ground calibration unit provides helium and zero air flows to periodically determine the reflectivity of the cavity mirrors using known Rayleigh scattering cross sections. The precision (1<span class="inline-formula"><i>σ</i></span>) for laboratory measurements is 43 ppt NO<span class="inline-formula"><sub>2</sub></span> in 1 s and 7 ppt NO<span class="inline-formula"><sub>2</sub></span> in 30 s. Measurement of air with known NO<span class="inline-formula"><sub>2</sub></span> mixing ratios in the range of 0–70 ppb agreed with the known values within 0.3 % (slope <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M9" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>=</mo><mn mathvariant="normal">0.997</mn><mo>±</mo><mn mathvariant="normal">0.007</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="78pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="070c85d9bb34c1e2574f428ab72c4964"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="amt-15-6643-2022-ie00001.svg" width="78pt" height="10pt" src="amt-15-6643-2022-ie00001.png"/></svg:svg></span></span>; <span class="inline-formula"><i>r</i><sup>2</sup>=0.99983</span>). We demonstrate instrument performance using vertical profiles of the NO<span class="inline-formula"><sub>2</sub></span> mixing ratio acquired on board an uncrewed aerial vehicle between 0 and 110 m above ground level in Boulder, Colorado.</p>https://amt.copernicus.org/articles/15/6643/2022/amt-15-6643-2022.pdf
spellingShingle C. C. Womack
C. C. Womack
S. S. Brown
S. S. Brown
S. J. Ciciora
R.-S. Gao
R. J. McLaughlin
M. A. Robinson
M. A. Robinson
Y. Rudich
R. A. Washenfelder
A lightweight broadband cavity-enhanced spectrometer for NO<sub>2</sub> measurement on uncrewed aerial vehicles
Atmospheric Measurement Techniques
title A lightweight broadband cavity-enhanced spectrometer for NO<sub>2</sub> measurement on uncrewed aerial vehicles
title_full A lightweight broadband cavity-enhanced spectrometer for NO<sub>2</sub> measurement on uncrewed aerial vehicles
title_fullStr A lightweight broadband cavity-enhanced spectrometer for NO<sub>2</sub> measurement on uncrewed aerial vehicles
title_full_unstemmed A lightweight broadband cavity-enhanced spectrometer for NO<sub>2</sub> measurement on uncrewed aerial vehicles
title_short A lightweight broadband cavity-enhanced spectrometer for NO<sub>2</sub> measurement on uncrewed aerial vehicles
title_sort lightweight broadband cavity enhanced spectrometer for no sub 2 sub measurement on uncrewed aerial vehicles
url https://amt.copernicus.org/articles/15/6643/2022/amt-15-6643-2022.pdf
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