Uncertainty analysis of spatiotemporal characteristics of haze pollution from1961 to 2017 in China

Özet

The definition of haze day is still controversial, and there are different data sources for haze data in China. Thisstudy analyzes the uncertainty of haze data in China, which is a prerequisite for studying haze trends. The overalltrends defined by different approaches were relatively consistent, but the average values were different. Theannual number of haze days defined by visibility and relative humidity was higher than the number defined bymanual observation. The correlation coefficient between the two datasets for the whole country was 0.92, andranged from 0.7 to 0.9 for different regions. The similarity between the trends of haze days by different ap-proaches was greater in the Yangtze River Delta region and the Pearl River Delta region than in the SouthwestRegion. Limited impact of relative humidity on the trends of haze days was detected in China and differentregions. The influence of station screening was also investigated. Station screening had no effect on the annualaverage number of haze days and the long-term trend. Based on the above analysis, the haze data defined byvisibility and relative humidity were chosen to study the spatial and temporal distributions for China. In terms ofseasons, haze days were most frequent in winter and least frequent in summer. Except for the Northwest region,the number of haze days increased noticeably after 1980. Our results can further deepen the understanding ofthe characteristics of haze pollution, and support the study of the causes of haze pollution in China.