The volcanic degassing of halogens, and especially of the heavier Br and I, received increased attention over the last 20 years due to their significant effect on atmospheric chemistry, notably the depletion of stratospheric ozone. While the effect of melt composition on halogen diffusion, solubility, or fluid-melt partitioning in crustal magma chambers has been thoroughly studied, structural...
Publications
Louvel M., Cadoux A., Brooker R., Proux O. and Hazemann J.-L., 2020, New insights on Br speciation in volcanic glasses and structural controls on halogen degassing. American Mineralogist Special Collection “Halogens in Planetary Systems”, 105, 795 - 802.
Klobas, J. E. and Wilmouth, D. M.: UV spectroscopic determination of the chlorine monoxide (ClO) ∕ chlorine peroxide (ClOOCl) thermal equilibrium constant, Atmos. Chem. Phys., 19, 6205–6215, https://doi.org/10.5194/acp-19-6205-2019, 2019.
The thermal equilibrium constant between the chlorine monoxide radical (ClO) and its dimer, chlorine peroxide (ClOOCl), was determined as a function of temperature between 228–301K in a discharge flow apparatus using broadband UV absorption spectroscopy. A third law fit of the equilibrium values determined from the experimental data provides the expression: Keq = 2.16×10−27 e(8533±...
Clapp, C. E., & Anderson, J. G. ( 2019). Modeling the effect of potential nitric acid removal during convective injection of water vapor over the Central United States on the chemical composition of the lower stratosphere. Journal of Geophysical Research: Atmospheres, 124, 9743-9770. https://doi.org/10.1029/2018JD029703
Tropopause‐penetrating convection is a frequent seasonal feature of the Central United States climate. This convection presents the potential for consistent transport of water vapor into the upper troposphere and lower stratosphere (UTLS) through the lofting of ice, which then sublimates. Water vapor enhancements associated with convective ice lofting have been observed in both in situ and...
Clapp, C. E., Smith, J. B., Bedka, K. M. & Anderson, J. G. (in press). Identifying Source Regions of Warm Season North American Cross-tropopause Convection and of the Distribution of Convective Outflow. Journal of Geophysical Research: Atmospheres.
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Clapp, C. E. & Anderson, J. G. (in preparation). Modeling the effect of gravity wave temperature perturbations on chlorine activation in the lower stratosphere. Journal of Geophysical Research: Atmospheres.
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Klobas, J. Eric and David M. Wilmouth. 2019. Volcanogenic chlorofluorocarbons and the recent CFC anomalies. Harvard University, Cambridge, MA. https://dash.harvard.edu/handle/1/39913598.
This document is a white paper prepared at the request of the Scientific Assessment Panel (SAP) of the Montreal Protocol. We briefly review the literature regarding the volcanogenic production of chlorofluorocarbons within the context of the East Asian CFC-11 emissions anomaly first described in 2018. We conclude that volcanic emissions of CFC-11 cannot account for the observed emissions anomaly.
Wilmouth, D. M., and D. S. Sayres (2019), Rayleigh scattering cross sections of argon, carbon dioxide, sulfur hexafluoride, and methane in the UV-A region using Broadband Cavity Enhanced Spectroscopy, Journal of Quantitative Spectroscopy and Radiative Transfer 234, 32-39, doi:10.1016/j.jqsrt.2019.05.031.
Accurate Rayleigh scattering cross sections are important for understanding the propagation of electromagnetic radiation in planetary atmospheres and for calibrating mirror reflectivity in high finesse optical cavities. In this study, we used Broadband Cavity Enhanced Spectroscopy (BBCES) to measure Rayleigh scattering cross sections for argon, carbon dioxide, sulfur hexafluoride, and methane...
Wilkerson, J., R. Dobosy, D. S. Sayres, C. Healy, E. Dumas, B. Baker, and J. G. Anderson (2019), Permafrost nitrous oxide emissions observed on a landscape scale using the airborne eddy-covariance method, Atmos. Chem. Phys., 19 (7), 4257-4268, doi:10.5194/acp-19-4257-2019.
The microbial by-product nitrous oxide (N2O), a potent greenhouse gas and ozone depleting substance, has conventionally been assumed to have minimal emissions in permafrost regions. This assumption has been questioned by recent in situ studies which have demonstrated that some geologic features in permafrost may, in fact, have elevated emissions comparable to those of tropical soils. However,...
Burkholder, J. B., S. P. Sander, J. Abbatt, J. R. Barker, C. Cappa, J. D. Crounse, T. S. Dibble, R. E. Huie, C. E. Kolb, M. J. Kurylo, V. L. Orkin, C. J. Percival, D. M. Wilmouth, and P. H. Wine "Chemical Kinetics and Photochemical Data for Use in Atmospheric Studies, Evaluation No. 19," JPL Publication 19-5, Jet Propulsion Laboratory, Pasadena, 2019, http://jpldataeval.jpl.nasa.gov.
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Wilmouth, D. M., R. J. Salawitch, and T. P. Canty, "Stratospheric Ozone Depletion and Recovery," a chapter in Green Chemistry: An Inclusive Approach, Torok, B., and T. Dransfield (Eds.) Elsevier Publishing, 2018, p.177–209.
This chapter provides an overview of the depletion of Earth’s ozone layer due to human activity and the eventual recovery due to legislation that banned ozone-depleting substances (ODSs) such as chlorofluorocarbons (CFCs) and bromine-bearing halon gases. The importance of ozone in protecting life on Earth is introduced, followed by details on how the release of CFCs and halons led to significant...