Understanding temporal temporal patterns and characteristics of air quality in Beijing: A local and regional perspective

Sources, characteristics and seasonal variation of airborne pollutants in China, especially in Beijing, have been massively examined. However, most studies analyze local air quality from an isolated perspective and interactions between local and regional air quality have not been fully considered. This research attempts to evaluate Beijing air quality at the local and regional scale. The weighted cross correlogram spectral matching (CCSM) and convergent cross mapping (CCM) method are employed for similarity and causality analysis respectively. At the local scale, the air quality in Beijing experiences frequent and sudden change, yet changes smoothly across a day's time. At the regional scale, the air quality in Beijing and four neighboring cities is compared. The result suggests that although air quality in Beijing and neighboring cities is of some differences, strong bidirectional coupling exists between the local and regional air quality. The research indicates that air quality in Beijing is better than the general situation in this region, and Tianjin should be a good comparative site for monitoring and evaluating air quality in Beijing. This research provides a feasible methodology for comprehensive analysis of local air quality at multiple scales, which may shed some lights on the forthcoming implementation of local air quality evaluation. (C) 2015 Elsevier Ltd. All rights reserved.