Fractality in PM2.5 Concentrations During the Dry and Wet Season over Indo-Gangetic Plain, India

The study of temporal variations in the PM2.5 concentrations during the dry and wet periods can be useful to policymakers in air quality assessment and management. Fractal behavior in PM2.5 concentration at various locations over Indo-Gangetic Plain (IGP) is studied using multifractal detrended fluctuation analysis. The washout effect of rainfall on the temporal characteristics of PM2.5 concentration has not been studied earlier. Twenty-four-hour PM2.5 concentration time series during 2015-2017 at 5 locations, namely, Agra, Delhi, Varanasi, Lucknow, and Kanpur, over IGP is therefore selected for the study. Notwithstanding the dry or rainy season, the multifractal properties are observed in the PM2.5 time series. However, it has been learnt that during the wet period, the multifractal strength is reduced. Evaluating the multifractality's origin of PM2.5 data series suggested the contribution of irregular probability distribution and long-range correlations over two different periods. The prediction model for PM2.5 concentrations can be developed using knowledge about the time series behavior. The information could improve air quality evaluations and our comprehension of the processes that control the evolution of air pollutant concentrations over time.

Automated summary

The study examines the temporal variations in PM2.5 concentrations during dry and wet periods using multifractal detrended fluctuation analysis. The study focuses on the Indo-Gangetic Plain region and explores the washout effect of rainfall on PM2.5 concentration characteristics. The results show multifractal properties in the PM2.5 time series regardless of the season, with reduced multifractal strength during the wet period. The findings suggest the contribution of irregular probability distribution and long-range correlations to the multifractality of PM2.5 data series.