Study On The Relationship Between Air Pollution And PM2.5 Based On Asymmetric Multifractal

Air pollution has always been the focus of social attention,and with the development of the economy,air pollution is getting worse.In recent years,PM2.5 has attracted more attention as an important air pollutant.How to accurately analyze and effectively predict it has become a hot topic in current research.However,the complexity and nonlinearity of meteorological environment data make it difficult to study.Therefore,this paper introduces fractal theory and studies the variation trend and influencing factors of PM2.5 in various seasons in Hangzhou based on fractal theory.When studying the fractal features of PM2.5,based on the traditional multifractal,this paper introduces the asymmetric MF-DMA method.By this method,the multifractal characteristics of the PM2.5 time series on different trends can be further captured.When exploring the cause of the asymmetric multifractal of PM2.5 time series,the existing data random rearrangement method can only obtain the cause of multifractal.Therefore,this paper innovatively introduces Box-Cox transform and combines random rearrangement method,then obtained the cause of the asymmetric multifractal.In the study of the cross-correlation between PM2.5 and other air pollutants in Hangzhou,this paper introduces the asymmetric MF-DCCA method.Compared with the traditional MF-DCCA method,this method can well describe the fractal features of the cross-correlation of time series on different trends.In addition,this paper adopts the moving average detrending trend to improve the original polynomial fitting detrending trend,which effectively eliminates the pseudo-fluctuation error caused by the discontinuity of the dividing point in the polynomial fitting,and increases the calculation accuracy.On the basis of correlation,this paper further explores the causal relationship between PM2.5 and other air pollutants in Hangzhou,and introduces the MF-DCCA method based on wave conduction.This method can detect the cross-correlation of two time series on different lag times.By analyzing the change of cross-correlation,the direction of fluctuating conduction and conduction time between the two can be obtained.Through the asymmetric multifractal analysis of PM2.5 and other air pollutants in Hangzhou,the finer fractal features of PM2.5 in different trends were obtained,and the general rule of interaction between PM2.5 and other pollutants was found.Provide some theoretical guidance for the governance of PM2.5.