OH-reactivity of volatile organic compounds at urban and rural sites across Canada: Evaluation of air quality model predictions using speciated VOC measurements

摘要: Abstract The total OH-reactivity resulting from volatile organic compound (VOC) oxidation (defined here as ∑ k OH [VOC]) is a measure of the potential an air mass to produce peroxy radicals. Organic radicals are key intermediate species in production ozone and secondary aerosol. In this study, routine VOC measurements 18 selected urban rural sites across Canada (data National Air Pollution Surveillance (NAPS) network) were used calculate OH-reactivity. Observationally-derived for VOCs was compared predictions Environment Canada's unified regional quality modelling system (AURAMS). model run two summer periods: between July 8 August 19, 2004 evaluation over eastern domain 23 September 9, 2005 western domain. Total predicted within factor most sites; however, model-measurement differences individual often larger offsetting contributions common. general, under-predicted centres with exception site Calgary, Alberta. higher alkene species, ALKE, largely responsible under-prediction at sites. Alberta showed over-prediction alkane ALKA. observationally-derived OH-reactivities aromatic compounds good agreement (AROM, TOLU). areas Canada, over-predicted due over-predictions contribution isoprene (ISOP). A sensitivity new Canadian vegetation database improved ISOP east; systematic still apparent.