Atmos. Chem. Phys., 12, 8009-8020, 2012
www.atmos-chem-phys.net/12/8009/2012/
doi:10.5194/acp-12-8009-2012
© 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
J. Mao1,2, X. Ren3, L. Zhang4, D. M. Van Duin4, R. C. Cohen5, J.-H. Park6, A. H. Goldstein6, F. Paulot7,*, M. R. Beaver7,**, J. D. Crounse7, P. O. Wennberg7, J. P. DiGangi8,***, S. B. Henry8, F. N. Keutsch8, C. Park9,****, G. W. Schade9, G. M. Wolfe10,*****, J. A. Thornton10, and W. H. Brune4
1Program in Atmospheric and Oceanic Sciences, Princeton University, Princeton, NJ, USA
2Geophysical Fluid Dynamics Laboratory, NOAA, Princeton, NJ, USA
3Air Resources Laboratory, NOAA, Silver Spring, MD, USA
4Department of Meteorology, Pennsylvania State University, University Park, PA, USA
5Department of Chemistry and Department of Earth and Planetary Science, University of California Berkeley, Berkeley, CA, USA
6Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, USA
7Environmental Science and Engineering, California Institute of Technology, Pasadena, CA, USA
8Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA
9Department of Atmospheric Sciences, Texas A&M University, College Station, TX, USA
10Department of Atmospheric Sciences, University of Washington, Seattle, WA, USA
*now at: School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
**now at: National Exposure Research Laboratory, Environmental Protection Agency, Research Triangle Park, NC, USA
***now at: Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ, USA
****now at: Department of Atmospheric Environmental Sciences, Pusan National University, South Korea
*****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 in a California forest. The new method gives on average only 40–60% 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 improved 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., Zhang, L., 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., Thornton, J. A., and Brune, W. H.: Insights into hydroxyl measurements and atmospheric oxidation in a California forest, Atmos. Chem. Phys., 12, 8009-8020, doi:10.5194/acp-12-8009-2012, 2012.
 
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