Study On Spatiotemporal Distribution And Influencing Factors Of Atmospheric Ozone In Four East Asian Countries

As an important component of the atmosphere,ozone plays an irreplaceable role in human socio-economic development and the normal operation of the ecological environment.In recent years,the problem of ozone pollution in East Asia has become prominent and increasingly serious.Studying the temporal and spatial distribution of ozone and related influencing factors in East Asia is of great significance to the atmospheric environment and climate change.Based on satellite remote sensing monitoring data from 2013 to 2021,this paper analyzes the temporal and spatial distribution characteristics,future trends,influencing factors,ozone sensitive control areas,transmission paths,and potential pollution source areas of tropospheric ozone column concentrations in four countries in East Asia:Japan,South Korea,North Korea,and Mongolia.The main research results are as follows:In terms of spatial distribution,Mongolia’s tropospheric ozone column concentration is at the lowest level in the four countries,with South Korea having the highest concentration,followed by Japan and North Korea;The annual spatial distribution of ozone column concentration in Mongolia has formed a distribution pattern of high,middle,and low concentrations around the country,while the annual distribution of ozone in Japan,South Korea,and North Korea is characterized by high concentrations in the south and low concentrations in the north;In terms of seasonal distribution characteristics,Japan’s summer presents the opposite distribution characteristics of the other three seasons,characterized by high temperatures in the north and south,while North Korea and South Korea appear high value regions at the border between the two countries in summer;In terms of monthly spatial distribution characteristics,it is found that May to August is a period when the north-south distribution pattern of ozone in Japan changes.Mongolia has formed a distribution characteristic of low in the southwest and high in the northeast in January to March and November to December,while South Korea and North Korea have a high value region at the border between the two countries in June to July.From 2013 to 2021,the average ozone column concentration in Japan,South Korea,North Korea,and Mongolia remained at 41.4DU,43DU,40.5DU,and 34.1DU,respectively.The annual variation of ozone column concentration in Mongolia was relatively stable,and Japan,South Korea,and North Korea showed a fluctuating upward trend;In the seasonal variation,summer is the season with the highest ozone column concentration in Japan,Korea,and Mongolia,while autumn in Mongolia is the season with the lowest ozone column concentration,while winter in Japan,Korea,and Mongolia is the season with the lowest ozone column concentration;The monthly variation of the tropospheric ozone column concentration in Mongolia presents a"double peak"trend,with the minimum mean appearing mostly in October and the maximum mean appearing mostly in July.The monthly variation of the tropospheric ozone column concentration in Japan,Korea,and North Korea presents an inverted"V"shape,with the minimum mean appearing mostly in December and the maximum mean appearing mostly in June.In the trend analysis,it was found that the tropospheric ozone column concentration in Japan,South Korea,and North Korea showed an increasing trend during the study period,while the ozone column concentration in the southern region of Mongolia also showed an increasing trend during the study period,but the ozone column concentration in the northern region between 50°N and 54°N showed a decreasing trend during the study period;Except for Mongolia,the Hurst index of the three countries in Japan,South Korea,and North Korea is mainly anti persistent.In the future,the ozone column concentration in Japan,South Korea,and North Korea will have a mean reciprocating phenomenon,and there will be a decreasing trend in the future.The southern regions of Mongolia,such as South Gobi Province and East Gobi Province,will have a moderate increase trend,while the northern regions will have a slight decrease trend.In the correlation analysis,the spatial correlation between ozone column concentration and temperature in Japan,Korea,Korea,and Mongolia is positive,while the spatial correlation with the uplift index is negative;In Mongolia,the ozone column concentration and relative humidity showed negative or non correlation in space,while in Japan,North Korea,and South Korea,they showed positive correlation in space.Path analysis found that formaldehyde column concentration had the most significant positive impact on ozone in Japan;North Korea and South Korea have the most significant negative impact on ozone from the rise index,while nitrogen dioxide has the most significant impact on ozone reduction in Mongolia.Analysis of ozone generation sensitive areas in Japan,South Korea,North Korea,and Mongolia shows that Mongolia continues to be a NO_x control area,while southern Korea is a mixed or transitional control area,while northern Korea is a NO_x control area.South Korea is mainly a mixed or transitional control area,and northern Japan is a NO_xcontrol area;Japan,South Korea,and North Korea are mostly VOC control areas or mixed control areas from January to March,and are mostly NO_x control areas from April to September,gradually transitioning to VOC control areas from September to December;An analysis of the formaldehyde nitrogen ratio(FNR)in the four capitals shows that the FNR in Ulaanbaatar have a decreasing trend,while the FNR in Pyongyang have a significant upward trend,while the FNR in Tokyo and Seoul have a slow upward trend.According to the analysis results of the backward trajectory transmission path and potential sources,the transmission path in Tokyo,Japan,in spring and winter is mainly in the northwest direction,while in summer,it is mainly in the southwest direction and the Pacific Ocean.In summer,its ozone is mainly affected by local sources;The transmission path in Seoul,South Korea,in spring,autumn,and winter is mainly northwest;In spring,the potential ozone source areas in Seoul are distributed in the Yellow Sea area,the western part of North Korea,and a small part of Liaoning Province,China.In summer,the main ozone source areas are the Yellow Sea area,while Seoul and surrounding areas in South Korea are important potential source areas.In autumn and winter,the ozone source areas are northwest potential source areas;Ulaanbaatar mainly has a northwest transmission path,but its potential source area is mainly in Mongolia.