Atmospheric Measurement Techniques (May 2021)

In situ observations of stratospheric HCl using three-mirror integrated cavity output spectroscopy

  • J. Wilkerson,
  • D. S. Sayres,
  • J. B. Smith,
  • N. Allen,
  • M. Rivero,
  • M. Greenberg,
  • T. Martin,
  • J. G. Anderson,
  • J. G. Anderson,
  • J. G. Anderson

DOI
https://doi.org/10.5194/amt-14-3597-2021
Journal volume & issue
Vol. 14
pp. 3597 – 3613

Abstract

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Stratospheric HCl observations are an important diagnostic for the evaluation of catalytic processes that impact the ozone layer. We report here in situ balloon-borne observations of HCl employing an off-axis integrated cavity output spectrometer (OA-ICOS) fitted with a reinjection mirror. Laboratory assessments demonstrated that the spectrometer has a 90 % response time of 10 s to changes in HCl and a 30 s precision of 26 pptv. The instrument was deployed alongside an ozone instrument in August 2018 on a balloon-borne descent between 20–80 hPa (29–18 km altitude). The observations agreed with nearby satellite measurements made by the Earth Observing System Microwave Limb Sounder within 10 % on average. This is the first time that stratospheric measurements of HCl have been made with ICOS and the first time any cavity-enhanced HCl instrument has been tested in flight.