Spatial and temporal distribution characteristics of PM2.5 concentration in global typical countries based on remote sensing products
In the context of globalization,PM2.5 pollution has become a global phenomenon.Understanding the spatial and temporal differential distribution of PM2.5 concentrations in differ-ent countries has become an increasingly important topic for governments.Taking 27 typical countries in the world as the research objects,Ensemble Empirical Mode Decomposition(EEMD),GIS map representation,and comparative research methods were used to analyze the spatial and temporal variation characteristics of PM2.5 pollution from 1998 to 2019.The results show that:① The trend fluctuation of PM2.5 in the global typical countries in the study area was divided into four types:'continuous rise','continuous fall','first rise and then fall'and'first fall and then rise.70％of the countries showed a trend of improving PM2.5 pollution during the study period;② Except for Africa,the monthly changes of countries in the same regions are sim-ilar;③ Compared with North America,Europe,and Oceania,Asia,the Middle East,and Africa have larger seasonal changes in PM2.5 concentrations;④ From the perspective of the average an-nual concentration,Pakistan,India,Bangladesh,Iran,Egypt,Saudi Arabia,Turkey and Nigeria had higher PM2.5 concentration in the past 20 years,which also have exceeded the PM2.5 transi-tion target I pollution level(35μg/m3)proposed by WHO.The comparative study of spatial and temporal differences of PM2.5 pollution under long time series can provide scientific reference for countries with different levels of economic development,and complement the global national macro scale PM2.5 concentration characteristics.
remote sensing productsEensemble Empirical Mode Decompositionglobal typi-cal countriesPM2.5spatiotemporal distribution
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