J. Eric Klobas's Publications

Østerstrøm, F. F., J. E. Klobas, R. P. Kennedy, A. Cadoux, and D. M. Wilmouth, Sensitivity of stratospheric ozone to the latitude, season, and halogen content of a contemporary explosive volcanic eruption. Nature Sci. Rep.13, 6457, 2023, doi: 10.1038/s41598-023-32574-9.

We present a systematic evaluation of the perturbation to the stratosphere from an explosive volcanic eruption injecting sulfur dioxide into the atmosphere, as a function of latitude, season, and injection gas halogen content in a chemistry-climate state representative of the present day (modeled as year 2025). Enhancements in aerosol surface area density and decreases in stratospheric ozone are...

Klobas, J. E., J. Hansen, D. K. Weisenstein, R. P. Kennedy, and D. M. Wilmouth, Sensitivity of iodine-mediated stratospheric ozone loss chemistry to future chemistry-climate scenarios. Front. Earth Sci.9, 617586, 2021, doi: 10.3389/feart.2021.617586.

As the chemical and physical state of the stratosphere evolves, so too will the rates of important ozone-destroying reactions. In this work, we evaluate the chemistry-climate sensitivity of reactions of stratospheric iodine, reporting the iodine alpha factor (the efficiency of ozone loss mediated by a single iodine atom relative to the ozone loss mediated by a single chlorine atom) and the iodine...

Klobas, J. E., D. K. Weisenstein, R. J. Salawitch, and D. M. Wilmouth, Reformulating the bromine alpha factor and equivalent effective stratospheric chlorine (EESC): Evolution of ozone destruction rates of bromine and chlorine in future climate scenarios. Atmos. Chem. Phys.20, 9459–9471, 2020, doi: 10.5194/acp-20-9459-2020.

Future trajectories of the stratospheric trace gas background will alter the rates of bromine- and chlorine-mediated catalytic ozone destruction via changes in the partitioning of inorganic halogen reservoirs and the underlying temperature structure of the stratosphere. The current formulation of the bromine alpha factor, the ozone-destroying power of stratospheric bromine atoms relative to...

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±...

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.

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...

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...