Observations of Volatile Organic Compounds over Hebei Province, China and Impact on Ozone Formation

In 2016, six of the top ten cities with the worst air quality were located in Hebei Province, China, experiencing numerous violations of WMO and Chinese air quality standards for both particulate matter (PM) and ozone (O₃). The Air chemistry Research In Asia (ARIAs) campaign supported 11 research flights collecting meteorological, trace gas, and aerosol measurements in Spring 2016 over Hebei Province. In addition, twenty-seven whole air samples (WAS) were collected at altitudes from 400 to 3500 m and analyzed for 54 non-methane hydrocarbons and 28 halocarbons, including CFCs. We find alkanes dominate the total volume mixing ratio of VOCs, but alkenes are responsible for 38% of the total VOC reactivity assessed by calculating the OH loss rates. By evaluating the influence of specific VOC species on ozone pollution production using photochemical ozone creation potential (POCP) and ozone formation potential (OFP), we find aromatics, alkenes/alkynes, and the halocarbon vinyl chloride are responsible for most of the formation of photochemical smog in Hebei. An observation-constrained box model called Framework for 0-Dimensional Atmospheric Modeling (F0AM) is used to study O₃ photochemical processes along the flight track and ground site in Xingtai. Pollution episodes are further examined using airborne data collected by the NASA Korea-United States Air Quality Study (KORUS-AQ) campaign in addition to archived ground and satellite data. Lastly, ARIAs observations are compared with aircraft measurements over Colorado’s Front Range, also located in the midlatitudes with similar geographic environment suffering from photochemical ozone pollution. Sources of VOCs in the Front Range include oil and natural gas operations and vehicular emissions, while in Hebei Province sources of VOCs comprise of biomass burning, vehicular emissions, manufacturing, and petrochemical processes including oil and natural gas.