Gravity-Current Driven Transport of Haze from North China Plain to Northeast China in Winter 2010-Part I: Observations

Haze exerts a large effect on visibility reduction and has serious impacts on air quality and human health. Understanding the sources and transport of haze is of importance to improve the regional air quality and evaluate its health effects. In this study, we investigated a typical haze episode that occurred in northeast (NE) China during 4-6 November 2010 by analyzing the ground PM10 measurements from 11 monitoring sites, aerosol Lidar observations, synoptic charts, MODIS satellite imageries, and back trajectories. Our analyses suggest that the regional haze formed in the North China Plain (NCP) under stagnant conditions can be transported to NE China in similar to 1-3 days across Bohai Bay and Liaodong Bay - a typical transport pathway associated with the topography of northern China. The haze episode appeared to evolve progressively from southwest to northeast in the region of NE China, in agreement with the appearance of PM10 peak values, wind patterns, MODIS images and the back trajectories of air masses. Due to the haze impact, NE China showed significantly elevated particulate matter pollution by a factor of similar to 4-6 with the peak concentrations reaching similar to 410 mu g m(-3). The results together indicate that the regional transport from the NCP has a significant contribution to the PM pollution in NE China, thus efforts to control the source emissions over the NCP would be effective to improve the air quality in NE China.