Publications

Klobas, J. E., and D. M. Wilmouth, UV spectroscopic determination of the chlorine monoxide (ClO) / chlorine peroxide (ClOOCl) thermal equilibrium constant. Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2018-1120, 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±...

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...

Dobosy, R., D. Sayres, C. Healy, E. Dumas, M. Heuer, J. Kochendorfer, B. Baker, and J. Anderson (2017), Estimating random uncertainty in airborne flux measurements over Alaskan tundra: Update on the Flux Fragment Method, J. Atmos. Oceanic Technol., in press; doi: 10.1175/JTECH-D-16-0187.1.

Airborne turbulence measurement gives a spatial distribution of air-surface fluxes that networks of fixed surface sites typically can not capture. Much work has improved the accuracy of such measurements and the estimation of the uncertainty peculiar to streams of turbulence data measured from the air. A particularly significant challenge and opportunity is to distinguish fluxes from different...

Anderson, J. G., D. K. Weisenstein, K. P. Bowman, C. R. Homeyer, J. B. Smith, D. M. Wilmouth, D. S. Sayres, J. E. Klobas, S. S. Leroy, J. A. Dykema, and S. C. Wofsy (2017), Stratospheric ozone over the United States in summer linked to observations of convection and temperature via chlorine and bromine catalysis, Proceedings of the National Academy of Sciences 114: E4905-E4913; doi: 10.1073/pnas.1619318114.

We present observations defining (i) the frequency and depth of convective penetration of water into the stratosphere over the United States in summer using the Next-Generation Radar system; (ii) the altitude-dependent distribution of inorganic chlorine established in the same coordinate system as the radar observations; (iii) the high resolution temperature structure in the stratosphere over the...

Sayres, D. S., R. Dobosy, C. Healy, E. Dumas, J. Kochendorfer, J. Munster, J. Wilkerson, B. Baker, and J. G. Anderson (2017), Arctic regional methane fluxes by ecotope as derived using eddy covariance from a low-flying aircraft, Atmos. Chem. Phys. 17(13): 8619-8633; doi: 10.5194/acp-17-8619-2017.

The Arctic terrestrial and sub-sea permafrost region contains approximately 30 % of the global carbon stock, and therefore understanding Arctic methane emissions and how they might change with a changing climate is important for quantifying the global methane budget and understanding its growth in the atmosphere. Here we present measurements from a new in situ flux observation system designed for...

Smith, J. B., D. M. Wilmouth, K. M. Bedka, K. P. Bowman, C. R. Homeyer, J. A. Dykema, M. R. Sargent, C. Clapp, S. S. Leroy, D. S. Sayres, J. M. Dean-Day, T. P. Bui, and J. G. Anderson (2017), A case-study of convectively sourced water vapor observed in the overworld stratosphere over the United States, J. Geophys. Res. Atmos. 122, doi:10.1002/2017JD026831.

On 27 August 2013, during the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys field mission, NASA's ER‐2 research aircraft encountered a region of enhanced water vapor, extending over a depth of approximately 2 km and a minimum areal extent of 20,000 km2 in the stratosphere (375 K to 415 K potential temperature), south of...

Klobas, J. E., D. M. Wilmouth, D. K. Weisenstein, J. G. Anderson, and R. J. Salawitch (2017), Ozone depletion following future volcanic eruptions, Geophys. Res. Lett. 44, 7490-7499; doi: 10.1002/2017GL073972.

While explosive volcanic eruptions cause ozone loss in the current atmosphere due to an enhancement in the availability of reactive chlorine following the stratospheric injection of sulfur, future eruptions are expected to enhance total column ozone as halogen loading approaches pre-industrial levels. The timing of this shift in the impact of major volcanic eruptions on the thickness of the ozone...

Canty, T. P.R. J. Salawitch, and D. M. Wilmouth (2016), The kinetics of the ClOOCl catalytic cycleJ. Geophys. Res. Atmos.12113,76813,783, doi:10.1002/2016JD025710.

We use simultaneous in situ observations of [ClO] and [ClOOCl] obtained in the Arctic polar vortex to evaluate the kinetics of the ClOOCl catalytic cycle. Available laboratory measurements of the ClOOCl absorption cross sections, the ClO + ClO + M reaction rate constant, and the ClO/ClOOCl equilibrium constant are considered, along with compendium evaluations of these...

J. B. Burkholder, S. P. Sander, J. Abbatt, J. R. Barker, R. E. Huie, C. E. Kolb, M. J. Kurylo, V. L. Orkin, D. M. Wilmouth, and P. H. Wine "Chemical Kinetics and Photochemical Data for Use in Atmospheric Studies, Evaluation No. 18," JPL Publication 15-10, Jet Propulsion Laboratory, Pasadena, 2015, http://jpldataeval.jpl.nasa.gov.

Anderson, J. G., D. M. Wilmouth, J. B. Smith, and D. S. Sayres, UV Dosage Levels in Summer: Increased Risk of Ozone Loss from Convectively Injected Water Vapor, Science 337, 835 (2012).

The observed presence of water vapor convectively injected deep into the stratosphere over
the United States can fundamentally change the catalytic chlorine/bromine free-radical chemistry of the lower stratosphere by shifting total available inorganic chlorine into the catalytically active free-radical form, ClO. This chemical shift markedly affects total ozone loss rates and makes
the catalytic...

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