Three Dimensional Spatial And Temporal Distribution Of Global Aerosol Mass Concentration

At present,the main sources of obtaining aerosol mass concentration information at global scale are satellite remote sensing and model simulation.The accuracy of aerosol model simulation is very dependent on the accurate emission list,while the improvement of emission list quality depends on the accurate observation facts.The development of satellite remote sensing is very important to accurately grasp the global aerosol distribution.The improvement of hardware,software and data algorithm of satellite remote sensing is still the focus of current researches.The study of aerosol mass concentration distribution mainly depends on the advantages of passive remote sensing,such as large space range,high horizontal resolution,continuous observation time,etc.,but passive remote sensing still has the following obvious shortcomings:?1?lack of night information;?2?lack of high vertical resolution information;?3?high uncertainty of inversion in high albedo area;?4?seriously affected by cloud.Based on this,a set of aerosol mass concentration inversion method based on active remote sensing is developed in this paper to analyze the aerosol distribution characteristics in different regions of the world from the aerosol mass concentration.Based on the retrieved aerosol type and extinction coefficient data from CALIPSO,combined with AERONET photometer and ground aerosol mass concentration observation data,this paper constructs inversion parameter tables for different types of aerosols,and develops a set of intuitive,efficient and flexible inversion methods of PM₁₀0 and PM_2.5 concentration,aerosol type includes clean marine?CM?,clean continental?CC?,pure dust?DU?,polluted dust?PD?,polluted continental smoke?PC/SM?,raised smoke?ES?and dusty marine?DM?.By comparing with the data of ground stations in different regions of the world,the inversion method developed in this paper has outstanding performance in the inversion of PM₁₀ and PM_2.5 concentration under the condition of high concentration pollution.The correlation coefficient R² in the verification results of daytime and nighttime is higher than 0.7,which can be considered that the inversion results have high reliability.In the spring of northern hemisphere,the PM concentration in the daytime was significantly higher than that at night.In the daytime,the concentrations of PM₁₀ and PM_2.5 in Taklimakan Desert and Sahara Desert are higher than those in other seasons.The concentrations of aerosol transport belt in the Western Pacific are higher in spring and winter,but lower in autumn.In spring and winter,there is also a high concentration area in the equatorial convergence zone of the Pacific Ocean,but the concentration value is smaller than that in the equatorial radiation zone of the Atlantic Ocean.In summer in the northern hemisphere,PM₁₀ concentration is higher in northern India and the Middle East.Because of the low summer monsoon in the Bay of Bengal,the trend of pollution spreading to the sea during the day and night may be hindered,and PM₁₀and PM_2.5 concentrations increase during this period.In the high latitudes of the northern hemisphere,the difference of PM between day and night is obvious.During the autumn in the northern hemisphere,PM₁₀ and PM_2.5 in the northern part of South America were higher than those in other seasons.In addition,the average PM₁₀concentration over the southern hemisphere was higher than that in other three seasons,and the PM_2.5 value was lower.In the high latitude area of northern Siberia,the difference of PM concentration between day and night is obvious.PM₁₀ was higher in autumn than in other seasons,and pollutants were transported to high latitude.The highest mass concentration of Taklimakan Desert appears in spring,which is also the high season of dust transport and sandstorm time in China.In winter in the northern hemisphere,heating in northern China increased PM₁₀ significantly,and the diffusion conditions of coal-fired pollution at night were poor,which also led to the high concentration of PM₁₀ and PM_2.5 at night.In winter,the concentration of PM₁₀ in northern India,especially near the south slope of the Qinghai Tibet Plateau,is higher than that in other seasons.In winter,the concentrations of PM₁₀ and PM_2.5 in North America,Europe and Australia are also high,but they are very low at night.Due to human activities,the difference between day and night of PM₁₀ in North China,North India and Southeast Asia is large;the difference between day and night of PM₁₀ in Taklimakan Desert and Gobi area is mainly that the atmospheric conditions at night are more stable than that in daytime.Due to heating activities,the high incidence season of PM₁₀ in North China,Northeast China and India is winter,and the high incidence season of PM₁₀ in Taklimakan desert is spring.The summer monsoon makes Pakistan and northwest India in a low-pressure zone,which is affected by local and external aerosol sources.The concentration of PM₁₀ in this area increases obviously in summer,and the vertical height of PM₁₀ concentration area can reach 4 km.The thickness of the high value area of aerosol in the urban area of North China is generally2 km,and the diffusion conditions are poor in each season.The concentrations of CM,PC,PD and CC of PM_2.5 were higher in daytime than at night,while DM,ES and Du were the opposite.In the latitude range of 0-30°N,DU can cause high mass concentration over the Atlantic Ocean.In the Atlantic Ocean and Antarctica,PM_2.5.5 with DU and DM aerosol types is higher at night than in the daytime.CM appears most frequently near the surface or at sea.On the land,the mass concentration of all types of aerosols is higher in the daytime than at night,but the results are different in the sea.The PM_2.5 concentrations of CM,PC,PD and CC were higher in daytime than in nighttime,while DM,ES and DU were the opposite.Du and DM are the types of aerosols that cause high concentrations in the equatorial convergence zone of the North Atlantic and most of the southern hemisphere.Over the Atlantic and Antarctica,the PM_2.5 of DU and DM aerosol type is higher at night than in daytime.When the vertical transmission capacity of DU and ES is the strongest,the transmission height can reach more than 4km,which has an impact on the PM concentration at high altitude.The PM concentration at high altitude of DU in the dust source area in summer is higher than that in other seasons,and that in the high latitude sea area in the northern hemisphere in winter is higher.The second is the transmission capacity of PD,the transmission height is within 0-4km,and the seasonal distribution of PM₁₀ is not obvious.PC/SM is mainly used as a local source of pollution in the local area.The PM_2.5 concentration of CC is the smallest among the seven types of aerosols,and the average PM_2.5 concentration near the ground is about 20?g·m^-3.During the day,the areas with relatively high PM_2.5 concentration in surface CC are central Europe,northern Siberia,and North America.The areas with relatively high PM_2.5 concentration in nighttime CC are South America,Europe,and Antarctica,where the PM_2.5concentration in nighttime is higher than that in daytime.In the Arctic?67-82°N?,the high concentration areas of aerosols are mainly concentrated in the near surface,near sea level and 2-4km high altitude section.The aerosol concentration in summer is higher than that in winter,and the aerosol concentration in the high altitude and on the ground increases slightly year by year.The area with high concentration of PM_2.5 is mainly 2-4km,and the area with high concentration of pollution and marine aerosol is near the surface and offshore.The northwest of Siberia is heavily affected by dust,followed by dust,while the north of Europe is more seriously affected by pure dust than other types of aerosols.The temperature increasing effect in the northwest of Siberia is greater than that in the north of Europe,while the dust in the sea area from the north of North America to the north of Siberia is mainly PD,with many ES but a relatively low concentration.The overall absorption capacity of aerosols is weak,which makes the region show a decline temperature trend.In 2013-2016,the sea ice area declined sharply year by year,and the mass concentration of dust and smoke increased year by year.Aerosol contributed more and more to the melting of ice and snow in the Arctic and the climate change in the Arctic.The dust concentration in the high altitude increased year by year,heating the upper atmosphere,making the atmospheric structure more stable,which may cause the dust transported to the Arctic from a long distance to stay in the high altitude and bring the Arctic environmental belt To a great extent,on the other hand,the high-altitude accumulation of energy brought by long-distance transmission may increase the process of heating in the Arctic.