| Abstract: | PM_(2.5) has become an increasing public concern recently because of its visibility reduction and severe health risks. For the whole year of 2013, hourly PM_(2.5) data of 496 monitoring sites scattered in 74 cities of China are collected to analyze temporal and spatial variability of PM_(2.5) concentration. Different temporal scales(seasonal variation, monthly variation and daily variation) and spatial scales(urban versus rural, typical areas and national scale) are discussed. Results show that PM_(2.5) concentration changes significantly in both long-term and short-term scales. An apparent bimodal pattern exists in daily variation of PM_(2.5) concentration and the daytime peak appears around 10:00 am while the lowest concentration appears around 16:00 pm. Spatial autocorrelation analysis and Ordinary Kriging are used to characterize spatial variability. Moran's I of PM_(2.5) concentration in three typical regions, the Beijing-Tianjin-Hebei region, the Yangtze River Delta region and the Pearl River Delta region, is 0.906, 0.693, 0.746, respectively, which indicates that PM_(2.5) is strong spatial correlated. Spatial distribution of annual PM_(2.5) concentration simulated by Ordinary Kriging shows that 7.94 million km2(83%) areas fail in meeting the requirement of China's National Ambient Air Quality Standards Level-2(35 mg/m3) and there are at least three concentrated highly polluted areas across the country. |
