| In recent years,the issue of atmospheric pollution has become increasingly acute.Atmospheric aerosols,an essential component of the land-atmosphere-ocean system,significantly impact global ecological environments and climate change.With the deepening of global change research,atmospheric aerosols have become a key indicator for evaluating global climate change and an important research topic in climate change.The Belt and Road initiative,as the most promising international cooperation platform,has a wide geographical range and complex and diverse natural environments with significant ecological and environmental problems.Therefore,studying and analyzing the spatiotemporal variations of aerosol optical depth(AOD)and its influencing factors in the Belt and Road region can not only comprehensively understand the atmospheric pollution status of the area but also provide a decision-making reference for promoting sustainable development in the region.This study is mainly based on the MERRA2 aerosol remote sensing data from 1980 to 2020.Sen’s slope trend analysis and MK test methods were used to study the spatiotemporal variations of AOD in the Belt and Road" region.They analyzed the spatiotemporal variations of five types of aerosols,including black carbon aerosol,organic carbon aerosol,dust aerosol,sulfate aerosol,and sea salt aerosol.Additionally,a geographically weighted regression model was used to explore the influencing factors of the spatiotemporal variations of AOD.The main conclusions are as follows:(1)The multi-year mean of aerosol optical depth in the Belt and Road region from1980 to 2020 showed a slow decreasing trend.The spatial distribution characteristics of the annual,seasonal,and monthly mean of aerosol optical depth were the same.The high-value areas were mainly concentrated in eastern and northwestern China,the Arabian Peninsula,and the Indian Peninsula,and the low-value regions were primarily focused in the Qinghai-Tibet Plateau,northern Russia,and Papua New Guinea Island.The Sen’s slope and MK values verified the results well,showing a decreasing trend from south to north.The area between 15°N and 45°N is where the high and low aerosol optical depth values are concentrated.(2)There are pronounced regional differences in the distribution characteristics of each type of aerosol.The high-value areas of black carbon aerosols are mainly distributed in eastern China,India,Southeast Asia,and other places.The high-value measurements of dust aerosols are distributed primarily in northwestern China,the Arabian Peninsula,and the northern Indian Peninsula.The high-value areas of organic carbon aerosols are mainly distributed in western Sumatra,Kalimantan Island,and other places in Indonesia.The high-value measurements of sea salt aerosols are primarily distributed along the coastlines of the Arabian Peninsula,the Indian Peninsula,Southeast Asia,eastern China,the Philippines,Indonesia,and Papua New Guinea Island.The highvalue areas of sulfate aerosols are mainly distributed in the east of China and Europe.(3)According to the geographically weighted regression model results,the degree of influence of natural and social factors on regional aerosol optical depth shows evident spatial heterogeneity.Among them,temperature and population density have a mainly positive correlation,while precipitation and land use have a primarily negative correlation,with significant spatial differences. |
