Authors
Christopher F. Lee (CIRES,Department of Chemistry, University of Colorado Boulder), Margarita Reza (CIRES,Department of Chemistry, University of Colorado Boulder, Boulder, CO), Kyle Zarzana (Department of Chemistry, University of Colorado Boulder, Boulder, CO), Tyler Elgiar (Department of Chemistry & Biochemistry, Utah State University, Logan, UT), Liji David (Bingham Research Center, Utah State University, Vernal, UT), Seth Lyman (Department of Chemistry & Biochemistry, Utah State University, Logan, UT), Lynne Gratz (Environmental Program, Colorado College, Colorado Springs, UT), Noah Hirshorn (Department of Atmospheric Sciences, University of Utah, Salt Lake City, UT), Ian McCubbin (Department of Atmospheric Sciences, University of Utah, Salt Lake City, UT), Gannet Hallar (Department of Atmospheric Sciences, University of Utah, Salt Lake City, UT), Alessandro Franchin (NCAR/UCAR), Teresa Campos (NCAR/UCAR), Florian Obersteiner (Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany), Andreas Zahn (Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany), Cory Wolff (NCAR/UCAR), Rainer Volkamer (CIRES,Department of Chemistry, University of Colorado Boulder)

The role of atmospheric iodine atom as an oxidant of gaseous elemental mercury (GEM) has been deemed unimportant due to the relatively low amounts of iodine in the troposphere and the much faster thermal decomposition rate of the Hg-I adduct compared to Hg-Br and Hg-OH adducts. As a result, the latest implementation of atmospheric mercury chemistry in GEOS-Chem does not include reactions involving iodine atoms or iodine monoxide radicals (IO). Here, we re-examine the contribution of iodine atom and IO to the oxidation of GEM using co-located ground-based and airborne measurements of IO, BrO, NO2, O3, CO, CH4, GEM, oxidized mercury, and meteorology at Storm Peak Laboratory (SPL), Colorado (40.455 N, 106.744 W) during the TI3GER (Technological Innovation Into Iodine and GV-Aircraft Environmental Research) campaign in April 2022. These measurements, along with GEOS-Chem model output, are used to constrain a vertical profile of box model simulations utilizing the Framework for 0-D Atmospheric Modeling (F0AM). Results from this case study are contextualized using long-term observations of IO at SPL.