RAPID: Measurements of Hydroxyl Radicals, Sulfuric Acid, sCIs, Hydroperoxy Radicals and Organic Peroxy Radicals on the C-130 during FRAPPE

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This effort involves the deployment of a four-channel chemical ionization mass spectrometer (CIMS) system on the NSF/NCAR C-130 aircraft platform during the Front Range Air Pollution and Photochemistry Experiment (FRAPPE) field campaign scheduled to take place from July 16-August 16, 2014 in the Colorado Northern Front Range Metropolitan Area. FRAPPE is a campaign being lead by researchers from the National Center for Atmospheric Research (NCAR), with the participation of many university scientists. The FRAPPE campaign will run concurrently with the NASA DISCOVER-AQ (Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality) project.Chemical species to be measured through this effort include OH (hydroxyl radicals), HO2 (hydroperoxy radicals) and HO2+RO2 (hydroperoxy plus organic peroxy radicals), H2SO4 (sulfuric acid), and sCIs (the sum of stabilized Criegee radical Intermediates from the reactions of alkenes with ozone - O3). These measurements will improve characterization of the spatial and temporal variability of the oxidizing capacity of the sampled air masses during the campaign. They will also help to constrain the role of sulfuric acid in aerosol formation and growth, and quantify the importance of sCIs as an oxidant in the urban environment.The hydroxyl radical (OH) is the main oxidant in the lower atmosphere and the most significant one causing the formation of ozone. The measurements made in this study will make a vital contribution to modeling and forecasting air quality and in determining the sources of ozone in the Colorado Northern Front Range Metropolitan area. This effort is expected to lead to improved model representations of chemical processes occurring in the urban environment.