Impact of meteorological conditions on a nine-day particulate matter pollution event observed in December 2013, Shanghai, China

A severe particulate matter pollution event occurred in Shanghai from 1 to 9 December 2013. The mean hourly mass concentrations of PM2.5 and PM10 were 211.9 and 249.0 mu g/m(3), respectively. Reanalysis data, in situ, and remote-sensing measurements were used to examine the impacts of meteorological conditions on this event. It was found that the synoptic pattern of weak pressure, the reduced planetary boundary layer height, and the passage of two cold fronts were key factors causing the event. Four stages were identified during this event based on the evolution of its PM2.5 levels and weather conditions. The highest concentration of PM2.5 (602 mu g/m(3)) was observed in stage 3. High PM2.5 concentrations were closely associated with a low local ventilation index, with an average of 505 m(2)/s, as well as with the influx of pollutants from upstream, transported by the cold fronts. (c) 2015 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.