89th American Meteorological Society Annual Meeting

Sunday, 11 January 2009
Hydroxyl radical and sulfuric acid concentrations in Manitou Experimental Forest
Phoenix Convention Center
Talea Mayo, University of Texas, Austin, TX; and L. Mauldin, J. McGrath, and T. Petaja

The hydroxyl radical (OH) is an important chemical species.  It is the primary oxidizing agent in the troposphere, reacting with many pollutants and consequently maintaining the purity of the air.  It also plays an important role in the formation of sulfuric acid (H2SO4), which is important to aerosol production.  It is this role that made concentrations of OH a measurement of interest to the Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics and Nitrogen (BEACHON) Project, a study that aimed to improve earth system models by quantifying geophysical systems.  High reactivity, short lifespan, and low concentrations of OH make this molecule is particularly difficult to measure.  Chemical Ionization Mass Spectrometry (CIMS) is one reliable method of measuring OH concentrations and was used in this study.  The CIMS instrument measures OH by first converting it to sulfuric acid  by the addition of isotopically labeled sulfur dioxide (34SO2), allowing naturally occurring H2SO4 to also be measured.  Concentrations of both OH and H2SO4 were taken in Manitou Experimental Forest (MEF) in Manitou Springs, Colorado in summer 2008.  Decay rates of OH were also determined.  While OH concentrations and decay rates were unavailable at the conclusion of this research, concentrations of OH and H2SO4 as well as OH decay rates were measured in a similar study conducted in Morgan-Monroe Experimental Forest in May 2008

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