Relationship Between Aerosol Optical Thickness And Vegetation Coverage In Urumqi Study On Temporal And Spatial Variation Characteristics

In recent years,atmospheric aerosols and their optical properties have become more and more important in the study of climate change.Aerosol optical thickness is an important parameter of aerosol optical properties,which reflects the attenuation effect of aerosols on light.Many air pollution phenomena are directly or indirectly related to the physical and chemical properties and behavior of aerosols.As a northern city,Urumqi's atmospheric pollutants in aerosol state also cause a certain degree of harm to the urban atmospheric environment.Relevant studies have proved that vegetation can reduce the aerosol content in the atmosphere.Therefore,this paper hopes to use mod04 in 2010,2015 and 2020 aerosol product level 2 data and mod13a3 normalized vegetation index monthly products,using pixel dichotomy and Pearson correlation coefficient method to analyze the temporal and spatial distribution characteristics of Urumqi on a large scale,can provide ideas for the quantitative analysis of urban greening distribution and the distribution of atmospheric pollutants in aerosol state,and provide reference for the study of the correlation between vegetation coverage and aerosol optical thickness,Summarize and supplement the contents of urban greening suggestions for air pollutants in aerosol state.The following three conclusions are summarized through research and analysis:(1)temporal and spatial distribution characteristics of aerosol optical thickness in Urumqi from 2010 to 2020.In the time distribution,the high value of monthly change mainly appears in April and August,the high value of quarterly change appears in spring and summer,and the high value of annual change appears in 2020;In the spatial distribution,the change of aerosol optical thickness is mainly concentrated in Midong district and central urban area.The formation of this spatial distribution feature may be due to the existence of dust aerosol in Midong district located in Gurbantonggute desert,and the central urban area is not only the center of urban development of Urumqi,but also the center of development and exchange of the whole Xinjiang,which means that the human activities in the central urban area are frequent,and the increase of urban population and population density The number of motor vehicles,the accelerated development of construction industry and the increase of coal industry all participate in the process of aerosol optical thickness accumulation and increase.(2)Temporal and spatial distribution characteristics of vegetation coverage in Urumqi from 2010 to 2020.In the time distribution,the high value of monthly change mainly appears in July,August and September,the high value of quarterly change mainly appears in summer,and the high value of annual change mainly appears in 2010;In the spatial change,the change of vegetation coverage is mainly concentrated in the northwest edge of the central urban area and Urumqi county.In this decade,there is no vegetation coverage area,the area of low and medium vegetation coverage area decreases,and the area of very low vegetation coverage area and high vegetation coverage area increases.It shows that although the greening situation of Urumqi has improved,we should also pay attention to the changes of medium vegetation coverage area and very low vegetation coverage area.(3)Correlation between aerosol optical thickness and vegetation coverage from2010 to 2020.Pearson correlation analysis showed that there was a negative correlation between aerosol optical thickness and vegetation coverage.It shows that the aerosol optical thickness will decrease with the increase of vegetation coverage.It also further shows that increasing vegetation is conducive to alleviate the atmospheric pollution of aerosol state.This paper selects the aerosol optical thickness data and vegetation coverage data in 2010-2020 for correlation analysis.The results show that the relationship between aerosol optical thickness and vegetation coverage is mostly negative in monthly,quarterly and annual.(4)In addition,this paper uses geographic detectors to explore the factors that mainly affect the spatial distribution difference of aerosol optical thickness and vegetation coverage.The results show that temperature and precipitation have a great impact on the spatial diversity of aerosol optical thickness,and aerosol optical thickness and precipitation have a great impact on the spatial diversity of vegetation coverage.In order to explore the distribution differences of aerosol optical thickness and vegetation coverage on different land use types,the aerosol optical thickness and vegetation coverage in different land use types in corresponding years are quantitatively analyzed by using the land use data in 2010,2015 and 2020.The results show that when the land use types are urban and rural,industrial and mining,residential land,cultivated land and unused land,the value of aerosol optical thickness is larger.