Spatial And Temporal Distribution And Influencing Factors Of Absorptive Aerosols In Four East Asian Countries

In the process of the formation of high population density and rapid industrial development in East Asia,aerosols,as an important component of air pollution,are active,affecting the climate system,human health and social development.This paper uses Ultraviolet Aerosol Index(UVAI)from 2013 to 2021.The paper mainly analyzes the spatial and temporal distribution characteristics of ultraviolet absorbent aerosols in Japan,Korea,Korea and Mongolia in East Asia,predicts the trend change of UVAI in the future,analyzes the correlation between UVAI and the main influencing factors,and calculates the transmission path and pollution source area of absorbent aerosols.The main conclusions are as follows:Based on the analysis of spatial distribution of UVAI in four East Asian countries,it is concluded that the high value of UVAI in Japan is mainly concentrated in Hokkaido region,while the high value of UVAI in the western region of South Korea represented by Gyeonggi Province is always in the state.The high value of UVAI in North Korea is more obvious in the southwest coastal and eastern regions,while that in Mongolia is more significant in the South Gobi province,the Gobi Altai Province and Bayan Urige province.In the annual classification results,the coverage area of Grade 5 in Mongolia is much larger than that of the other three countries,but from the distribution proportion of high value areas in each country,the degree of UVAI pollution in the whole territory of North Korea is higher than that in other countries.In the results of seasonal scale classification,the high values of four countries were concentrated in winter,among which the spatial proportion of the fifth level in North Korea and South Korea was 62.26% and 40.44%,respectively.But for Mongolia,the high values in the west of Bayan Urige province and the southern UVAI in spring should also be paid attention to.Based on the analysis of UVAI time change in four East Asian countries,it is concluded that Japan,South Korea,North Korea and Mongolia all show an upward trend from 2013 to 2021.Among them,Mongolia contributed the highest annual growth rate of 33.65% in the study area from 2016 to 2017,while South Korea contributed the highest annual growth rate of 0.52 in 2018.The four seasons in East Asia showed the maximum value in winter and the minimum value in summer,and the maximum value in the four seasons appeared in the winter of 2017,with Korea(1.22)> North Korea(1.05)> Japan(0.95)> Mongolia(0.70).From the UVAI values of the corresponding seasons,the relative pollution degree of Japan is low.Mongolia is higher than the other three countries in spring and summer,and North and South Korea in autumn and winter,respectively.In 2017 and 2018,the grade ratio of the four East Asian countries showed that the grade ratio of the four countries in the later period was significantly higher than that in the earlier period,and the mean value of UVAI in these two years was either the highest value or the higher value during the study period of each country.Based on the analysis of the past and future trends of UVAI in four East Asian countries,it is concluded that the annual increase trend of Japan and South Korea is relatively significant during the study period of 9 years,and the distribution of future trends of Japan and South Korea is relatively concentrated,while the spatial distribution of the future trends of Korea and Mongolia presents a staggered state.On an annual scale,the future trends of central and southern Japan,North Gyeongsang and South Gyeongsang provinces in South Korea,and western Jeonhangai and Western Dongfang provinces in Mongolia showed significant increases.On the seasonal scale,the future increase trend of the four East Asian countries is mainly concentrated in winter.They should pay close attention to the coast of the Sea of Japan in Japan,the southeastern part of South Korea,the central and northern part of Korea represented by Jagang Province,and the eastern part of Mongolia represented by Dongfang Province.Based on the analysis of the correlation between UVAI and its influencing factors in four East Asian countries,the negative correlation between UVAI and precipitable water is relatively weak in the Seto Inland Sea coastal areas such as Oita Prefecture and Miyazaki Prefecture of Japan and the western Kusugur Province of Mongolia.This phenomenon is closely related to the geographical environment and industrial trade patterns of these two regions.The negative correlation between air temperature and UVAI is relatively weak in Japan and South Korea,and relatively strong in North Korea and Mongolia.It can be further speculated that the aerosol in North Korea and Mongolia is mainly coarse particles.The strong positive correlation between UVAI and uplift index was significant in northern Japan,western and northern South Korea,the whole of North Korea and central and southern Mongolia.The negative correlation between UVAI and tropospheric column ozone concentration is high in Aomori Prefecture in northern Japan and Kyushu region in southern Japan,parts of South Chungcheong Province and Gyeonggi Province in South Korea,North Pyongan Province and South Pyongan Province in western North Korea,and parts of Pyongyang.Based on the analysis of UVAI transmission paths and potential sources in four East Asian countries,it is concluded that: The transmission routes in Japan,South Korea,North Korea and Mongolia are mainly from the northwest direction.Among the selected representative points,Tokyo,Ulaanbaatar and Dalanzadegad are significantly affected by wind sources in spring and winter,while Sapporo,Seoul and Pyongyang are most significantly affected by wind sources in autumn and winter.From the distribution of WPSCF values,the potential sources of UVAI in the representative points of each country are mainly local sources,followed by the transmission sources in the surrounding administrative areas.The potential source of UVAI in Seoul appeared from South Korea in spring,autumn and winter.In Ulan Bator,transmission sources from the Republic of Tuva in Russia appeared in spring,and transmission sources from the Republic of Buryatia in Russia in winter.Daranzadegad UVAI potential source A transmission source from China’s Inner Mongolia Autonomous Region appeared in the autumn.