| In recent years,the problem of air pollution has become the focus of public attention,especially in East Asia,the pollution sources are complex.Natural or anthropogenic sources of pollutants emissions are relatively strong.And the emission of pollutants in East Asia has obvious regional distribution difference.The study on the emission of air pollutants in East Asia is of great significance to the study of regional air pollution and hemispheric(intercontinental)transport.Under the influence of weather system,the long distance transport of pollutants presents certain spatial structure characteristics.Aerosol extinction coefficient,aerosol optical thickness can reflect pollutant concentration.In addition,aerosol also has climatic,environmental and health effects.So aerosol extinction coefficient is developed.It is of great practical significance to study the spatial and temporal distribution of aerosol optical thickness.The spaceborne lidar system can not only realize long time continuous detection on a global scale,but also has its unique advantages in detecting the vertical distribution of aerosols.CALIOP is the first detector to provide global aerosol vertical distribution information,which provides valuable data for the three-dimensional distribution of aerosols in a large area,and reveals the source and migration of pollutants.After years of development and verification,CALIOP is the most mature data that can provide global high-resolution aerosol vertical distribution data.In this paper,the long-term vertical distribution characteristics of long distance transport of pollutants across the North Pacific are studied by using CALIOP,MODIS,OMI and MOPITT,as well as meteorological data.The main work and conclusions are as follows:1.The processing method of the secondary profile data of CALIOP was established.The secondary data of the fourth edition of CALIOP were screened by referring to the third edition of CALIOP data quality control screening strategy.All the data are processed on the basis of Matlab programming.2.In the North Pacific region(30°N~50°N,120°E~120°W),the vertical distribution of aerosol extinction coefficient shows a significant seasonal variation.The intensity of pollutant transport of transpacific in spring is the strongest,and the aerosol transport range is wide in spring.The pollution transport in spring mainly occurs above the upper air 2km.The highest vertical transport of pollution can reach about 8km,but the extinction coefficient above 2km in other seasons is very small.The upper air transport is the main transport in spring,and the aerosol level can still be maintained at the middle of the North Pacific Ocean,but mixed with the rising aerosol level on the west coast of North America,the influence degree is not great.3.he seasonal variation characteristics of aerosol optical thickness(CALIOP-AODO)at different altitudes were obtained from the average integral extinction coefficient of CALIOP study area.The changes of CALIOP-AOD below 2km were as follows: winter > spring > autumn > summer.The changes of CALIOP-AOD in the height of 2km-10 km were spring > summer > winter > autumn.Combined with MODIS's AOD products,the changes of the whole area were analyzed: spring > summer > winter > autumn.4.Based on the vertical distribution of the zonal extinction coefficient in spring,it is found that the aerosols at 20°N~25°N,125°E~130°E are discontinuous below 2km.The source of trace is Southeast Asia.Spring is the strongest season for biological combustion in Southeast Asia.MOPITT data was used to analyze CO and analyze the range of biological combustion in Southeast Asia.5.Vertical structure characteristics of spring aerosol are identified by CALOP vertical detection.Aerosol over 6km from140°E to 130 °W,the extinction coefficient of aerosols is approximately equal,and the extinction coefficient of aerosol is about 0.006/km.The extinction coefficient of aerosol gradually decreases with altitude increasing,and at high altitude 10 km,the extinction coefficient is about 0.001/km. |
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