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Improvements to a laser-induced fluorescence instrument for measuring SO₂ – impact on accuracy and precision

Rickly, Pamela S. and Xu, Lu and Crounse, John D. and Wennberg, Paul O. and Rollins, Andrew W. (2021) Improvements to a laser-induced fluorescence instrument for measuring SO₂ – impact on accuracy and precision. Atmospheric Measurement Techniques, 14 (3). pp. 2429-2439. ISSN 1867-8548. doi:10.5194/amt-14-2429-2021.

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This work describes key improvements made to the in situ laser-induced fluorescence instrument for measuring sulfur dioxide (SO₂) that was originally described by Rollins et al. (2016). Here, we report measurements of the SO₂ fluorescence emission spectrum. These measurements allow for the determination of the most appropriate bandpass filters to optimize the fluorescence signal, while reducing the instrumental background. Because many aromatic species fluoresce in the same spectral region as SO₂, fluorescence spectra were also measured for naphthalene and anisole to determine if ambient SO₂ measurements could be biased in the presence of such species. Improvement in the laser system resulted in better tunability, and a significant reduction in the 216.9 nm laser linewidth. This increases the online/offline signal ratio which, in turn, improves the precision and specificity of the measurement. The effects of these improvements on the instrumental sensitivity were determined by analyzing the signal and background of the instrument, using varying optical bandpass filter ranges and cell pressures and calculating the resulting limit of detection. As a result, we report an improvement to the instrumental sensitivity by as much as 50 %.

Item Type:Article
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URLURL TypeDescription ItemData ItemData
Rickly, Pamela S.0000-0002-8459-869X
Xu, Lu0000-0002-0021-9876
Crounse, John D.0000-0001-5443-729X
Wennberg, Paul O.0000-0002-6126-3854
Rollins, Andrew W.0000-0002-1020-3966
Alternate Title:Improvements to a laser-induced fluorescence instrument for measuring SO2 – impact on accuracy and precision
Additional Information:© Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License. Received: 27 Oct 2020 – Discussion started: 09 Nov 2020 – Revised: 01 Feb 2021 – Accepted: 12 Feb 2021 – Published: 26 Mar 2021. Data availability: The data collected for FIREX-AQ are available from the NASA/NOAA FIREX-AQ data archive at (last access: 23 April 2019, NASA/NOAA, 2019). The data collected for ATom-4 are available from the NASA ESPO data archive at (last access: 23 April 2019, NASA, 2019). Author contributions: The research was designed by PSR and AWR. Measurements were taken by PSR, AWR, LX, JDC, and POW. The paper was written by PSR, with contributions from all coauthors. The authors declare that they have no conflict of interest. We would like to thank the NASA DC-8 crew and management team for their support during ATom-4 and FIREX-AQ integration and flights. We thank Michelle Kim and Hannah Allen for operating CIT's CIMS instrument during ATom-4. This research was funded by the ATom investigation, under NASA's Earth Venture program, and the FIREX-AQ investigation, under NASA's Atmospheric Compostion: Upper Atmospheric Composition Observations program CE8 (CIT grant nos. NNX15AG61A and 80NSSC18K0660, respectively). Review statement: This paper was edited by Dwayne Heard and reviewed by two anonymous referees.
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Issue or Number:3
Record Number:CaltechAUTHORS:20210506-105320666
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Official Citation:Rickly, P. S., Xu, L., Crounse, J. D., Wennberg, P. O., and Rollins, A. W.: Improvements to a laser-induced fluorescence instrument for measuring SO2 – impact on accuracy and precision, Atmos. Meas. Tech., 14, 2429–2439,, 2021
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108990
Deposited By: Tony Diaz
Deposited On:06 May 2021 18:31
Last Modified:06 May 2021 18:31

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