| Aerosol optical depth(AOD),as an important optical property of atmospheric aerosol,is one of the most important factors for studying the effect of aerosol on climate,calculating aerosol load and evaluating the degree of air pollution.With the infiltration of remote sensing technology in the field of science and technology,it has been a hot spot for academic circle to monitor AOD by using remote sensing technology.Baotou is not only an important industry city of Inner Mongolia,but also a basic industrial base in the North of China,its industrial production scale and industrial structure have a significantly influence on urban air quality.But there has not been a research to regard Baotou as AOD over research area so far,so it is of great realistic significance to choose to do the research of reversion of AOD.Taking the MODIS image of research area as the data resource,the thesis uses ENVI5.1 software to pre-process the image.Combined with the oneself characteristics of the research area,with the help of 6S radiation transfer model,the thesis inverses the AOD over the research area from year 2005 to the year 2015 by using classical Dense Dark Vegetation.Because AOD has some relationship with meteorological factor,building up regression model of AOD and meteorological factor can provide new angles for studying the weather effect about the research area.What’s more,temporal-spatial characteristic analysis on AOD inversion results can provide factual basis for atmospheric aerosol’s spatial variation law.Besides that,the main conclusion of this thesis is as follow:Firstly,taking the MODIS image of research area as the data resource,the thesis makes use of ENVI5.1 software to pre-process the image,including MODIS image radiation correction,geometric rectification,cloud detection and so on.With the help of6 S radiation transfer model,the thesis inverses the AOD of research area by using classical dark target method.By comparing the inversion results with ground observations,the average relative error is 30.1%.Secondly,doing Pearson analysis on 11 years’ inversion results and observation data of meteorological factor,it can be found that AOD has relationship with air temperature and sunshine.Making a further analysis about AOD and air temperature,sunshine byusing unitary linear recursive analysis and nonlinear regression analysis to get the most suitable regression model,the result shows that AOD has distinct impact on Baotou’s temperature and sunshine.Thirdly,doing temporal-spatial characteristic analysis on AOD inversion results.From the angle of time series,it shows that AOD of research area is relatively low from March to October;it’s relatively high from November to next February;the image of annual AOD over time presents U-shaped,and it shows stable periodic inter-annual variability,which is mainly caused by cyclonic activity and warm supply.In the forth chapter,from the angle of spatial feature,in heating season,the AOD of research area is high in the North and low in the South,the highest region is in the South;in the no-heating season,the AOD of research area is low in the North and South in the South,the highest region is in the South.The reason why that is as follow: 1,the altitude of the North and the Middle area is comparatively high so that the need for heating supply is relatively large.2,the North area is plain.The economy is prosperous,the population is dense and the automobile emission volume is large,all which result in a aerosol particles gathered over the south area,and AOD ‘s distribution throughout the year.Lastly,the research results of this thesis are summarized and discussed,and the outlook for further works is pointed out. |
PDF Full Text Request