AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Investigating the Atmospheric Age Distribution of Primary and Secondary PM during a Severe Wintertime Pollution Episode
QI YING, Hongliang Zhang, Jianlin Hu, Texas A&M University
Abstract Number: 106 Working Group: Aerosol Chemistry
Abstract High PM2.5 concentrations are still frequently observed in many areas in China, particularly in winter. The occurrence of these events has been shown to be highly controlled by meteorological conditions with polluted and clean days often occurring periodically. One of the unresolved questions regarding the formation of PM2.5 during these high pollution events is how fresh and aged emissions interact and their respective contributions to the rapid increase of primary and secondary PM. A better understanding of how freshly emitted and aged PM2.5 and their precursors contribute to total PM2.5 concentrations will allow policymakers to design cost-effective urgent emission control measures when adverse meteorological conditions are predicted.
In this study, the Community Multiscale Air Quality (CMAQ) model with a unified source- and age-resolved gases and particle representation framework is applied to investigate the January 2013 severe PM2.5 pollution episode in China. In the age-resolved model, the same pollutant emitted at different times (thus with different atmospheric ages) are tracked independently through the model simulations of emission, transport, transformation and removal processes so that the age distribution of the pollutant can be directly determined. To determine the age-distribution of secondary PM2.5 components, such as ammonium nitrate, their gas phase precursors are also modeled as age-resolved mixtures using a modified gas phase chemical mechanism. We expect to present, based on the modeling results, the hour-by-hour evolution of the age-distribution of elemental carbon (EC), organic carbon (OC), nitrate (NO3-), sulfate (SO42-) and ammonium ion (NH4+) and the precursor gases at major urban areas as well as in regional scale during the one-month high pollution period. The correlation of atmospheric age with meteorological parameters will be study to better understand how meteorological conditions affect the accumulation and retaining of pollutants.