Analysis and accurate prediction of ambient PM2.5 in China using Multi-layer Perceptron

Whether PM2.5 can be long-range transported and what role secondary inorganic aerosols play in the episodes of haze have aroused numerous debates. In this work, Multi-layer Perceptron (MLP) is used to analyze and predict ambient PM2.5 in eight regional core cities in China to resolve the clashes, and the conclusions are listed as follows. Gaseous air pollutants (SO2, NO2, O-3 and CO) are way more momentous than meteorological conditions in shaping PM2.5. PM2.5 level is dominated by the ups and downs of gaseous air pollutants, indicating the pre-dominance of secondary inorganic aerosols and the existence of thermodynamic equilibrium between PM2.5 and gaseous air pollutants. The secondary PM2.5 tends to be generated within one hour. We quantitatively demonstrate that the primary emissions change and long-range transport are ubiquitously and conspicuously insignificant throughout the main cities of China and reductions of the gaseous air pollutants are most essential for regulating PM2.5. Furthermore, the phenology of local flora as the minor cause and lopsided thermodynamic equilibrium shift triggered by temperature change as the major cause elicit the severity of PM2.5 in wintertime-for every Celsius degree of temperature drop, PM2.5 increases by 5.9 mu g/m(3).