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Atmos. Chem. Phys. Discuss., 12, 6715-6744, 2012
www.atmos-chem-phys-discuss.net/12/6715/2012/ doi:10.5194/acpd-12-6715-2012 © Author(s) 2012. This work is distributed under the Creative Commons Attribution 3.0 License. |
Insights into hydroxyl measurements and atmospheric oxidation in a California forest
1Department of Meteorology, Pennsylvania State University, University Park, PA, USA
2Department of Chemistry and Department of Earth and Planetary Science, University of California Berkeley, Berkeley, CA, USA
3Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, USA
4Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
5Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA
6Department of Atmospheric Sciences, Texas A&M University, College Station, TX, USA
7Department of Atmospheric Sciences, University of Washington, Seattle, WA, USA
*now at: Geophysical Fluid Dynamics Laboratory, NOAA, Princeton, NJ, USA
**now at: Air Resources Laboratory, NOAA, Silver Spring, MD, USA
***now at: Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ, USA
****now at: Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA, USA
*****now at: Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA
Abstract. The understanding of oxidation in forest atmospheres is being challenged by measurements of unexpectedly large amounts of hydroxyl (OH). A significant number of these OH measurements were made by laser-induced fluorescence in low-pressure detection chambers (called Fluorescence Assay with Gas Expansion (FAGE)) using the Penn State Ground-based Tropospheric Hydrogen Oxides Sensor (GTHOS). We deployed a new chemical removal method to measure OH in parallel with the traditional FAGE method. The new method gives on average only 40–50% of the OH from the traditional method and this discrepancy is temperature-dependent. Evidence indicates that the new method measures atmospheric OH while the traditional method is affected by internally generated OH, possibly from oxidation of biogenic volatile organic compounds. The agreement between OH measured by this new technique and modeled OH suggests that oxidation chemistry in at least one forest atmosphere is better understood than previously thought.
Citation: Mao, J., Ren, X., Brune, W. H., Van Duin, D. M., Cohen, R. C., Park, J.-H., Goldstein, A. H., Paulot, F., Beaver, M. R., Crounse, J. D., Wennberg, P. O., DiGangi, J. P., Henry, S. B., Keutsch, F. N., Park, C., Schade, G. W., Wolfe, G. M., and Thornton, J. A.: Insights into hydroxyl measurements and atmospheric oxidation in a California forest, Atmos. Chem. Phys. Discuss., 12, 6715-6744, doi:10.5194/acpd-12-6715-2012, 2012.