Direct measurement of ozone production rates in an urban environment

Atmospheric ozone production rates are usually calculated using measured or modeled concentrations of nitric oxide (NO) and peroxy radicals (HO2 and RO2). However, measured and modeled peroxy radical concentrations often disagree, thus increasing the uncertainty in the calculated ozone production rates. The Measurement of Ozone Production Sensor (MOPS) has been developed to obtain a direct measurement of the rate of ozone production in the atmosphere. The new technique uses a continuous ambient air flow through two 10L environmental chambers exposed to solar radiation, one of which is covered with a UV-blocking film, a highly efficient dioxide-to-ozone conversion unit, and a modified ozone analyzer. The underlying basis for the operation of the new instrument is the differential measurement of ozone produced in both chambers. The deployment of the instrument in Houston during the SHARP 2009 campaign offered a diverse set of scenarios in terms of pollution and meteorological conditions to test the capabilities of the MOPS in the field. Preliminary results will be presented.