Articles | Volume 9, issue 9
Atmos. Meas. Tech., 9, 4601–4613, 2016
Atmos. Meas. Tech., 9, 4601–4613, 2016

Research article 20 Sep 2016

Research article | 20 Sep 2016

A laser-induced fluorescence instrument for aircraft measurements of sulfur dioxide in the upper troposphere and lower stratosphere

Andrew W. Rollins1,2, Troy D. Thornberry1,2, Steven J. Ciciora2, Richard J. McLaughlin1,2, Laurel A. Watts1,2, Thomas F. Hanisco3, Esther Baumann4, Fabrizio R. Giorgetta4, Thaopaul V. Bui5, David W. Fahey1,2, and Ru-Shan Gao2 Andrew W. Rollins et al.
  • 1Cooperative Institute for Research in Environmental Sciences, Boulder, CO, USA
  • 2NOAA Earth System Research Laboratory, Chemical Sciences Division, Boulder, CO, USA
  • 3NASA Goddard Space Flight Center, Greenbelt, MD, USA
  • 4National Institute of Standards and Technology, Boulder, CO, USA
  • 5NASA Ames Research Center, Moffett Field, CA, USA

Abstract. This work describes the development and testing of a new instrument for in situ measurements of sulfur dioxide (SO2) on airborne platforms in the upper troposphere and lower stratosphere (UT–LS). The instrument is based on the laser-induced fluorescence technique and uses the fifth harmonic of a tunable fiber-amplified semiconductor diode laser system at 1084.5 nm to excite SO2 at 216.9 nm. Sensitivity and background checks are achieved in flight by additions of SO2 calibration gas and zero air, respectively. Aircraft demonstration was performed during the NASA Volcano-Plume Investigation Readiness and Gas-Phase and Aerosol Sulfur (VIRGAS) experiment, which was a series of flights using the NASA WB-57F during October 2015 based at Ellington Field and Harlingen, Texas. During these flights, the instrument successfully measured SO2 in the UT–LS at background (non-volcanic) conditions with a precision of 2 ppt at 10 s and an overall uncertainty determined primarily by instrument drifts of ±(16 % + 0.9 ppt).

Short summary
In situ measurements of SO2 in the tropical UT–LS have been scarce, in part due to limitations of existing instrumentation. Here we present a new laser-induced fluorescence instrument capable of measuring SO2 in the UT–LS region at single part-per-trillion (ppt) mixing ratios and demonstrate it on the NASA WB-57F aircraft up to 19.7 km altitude.