ACOM Seminar: Constraining the stratospheric sulfur budget: aircraft observations of SO2 in the Tropical UT/LS


Title: Constraining the stratospheric sulfur budget: aircraft observations of SO2 in the Tropical UT/LS

Speaker: Andrew Rollins , NOAA Earth System Research Laboratory

Abstract:  Oxidation of sulfur dioxide (SO2) in the Tropical UT/LS leads to intense nucleation of new particles that may be globally distributed, and SO2 transported through this region has been suggested to be a major source gas for aerosols in the stratosphere even during volcanically quiescent periods. In-situ measurements of SO2 in the tropical tropopause region to inform these processes have however been nearly absent from the observational record. We have recently developed a new laser induced fluorescence instrument for in-situ measurement of SO2 on high-altitude research aircraft and deployed the instrument during three aircraft campaigns spanning 2015 –2017. These flights provided more than 130 hours of observations up to 19.7 km altitude spanning 1°S – 45°N latitude. In this presentation I will provide an overview of these recent observations, and compare the measurements with satellite observations (MIPAS, ACE-FTS) and global models (WACCM, GEOS-5). While a few of the UT observations show that relatively high values of up to ~ 100 pptv may result from minor volcanoes and transport of pollution, the majority of our measurements indicate that typical tropopause SO2 concentrations are near 5 pptv. This low mixing ratio if globally representative is insufficient to be a major contributor to the total budget of stratospheric aerosols.

Date:  Monday, February 12, 2018Time:  Refreshments 3:15pm, Seminar 3:30pm Location: NCAR Foothills Laboratory - FL2-1022, Large Auditorium Live webcast:


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Announcement Timing: 
Monday, February 5, 2018 to Monday, February 12, 2018
Calendar Timing: 
Tuesday, February 13, 2018 - 5:30am to 6:30am

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