Study On The Correlation Between The MODIS AOD And The Corcentration Of PM_2.5 In Guangzhou City

In recent years,with the rapid development of China's society and economy,air quality is getting more and more attention.Aerosol is the basis and premise that forms the haze,the various pollutants which come from human activities includes the direct aerosol and all kinds of gaseous pollutants,these things can become the haze through the reaction of photochemistry,resulting in the increase of PM2.5concentration which is harmful to human health.Therefore,the use of satellite remote sensing technology to carry out air quality monitoring work has practical significance.The paper takes Guangzhou as the study area,and the Terra-MODIS satellite remote sensing image data as the sample data that is from July 2015 to June 2016 shot on sunny days,using the mature dark pixel method,showing the everyday aerosol optical depth of Guangzhou,and analyze the relationship between AOD and PM2.5 concentration combined with the ground environment,weather station data to establish the regression fitting model to estimate the concentration of the partical,realizing the purpose of real-time dynamic monitoring of atmospheric environmrnt.Based on the above research methods,the conclusions are as follows:(1)Inversion of the aerosol optical depth of the Guangzhou area by using the dark pixel algorithm,the results show that in the case of stable weather conditions,the general trend of AOD distribution in Guangzhou is increasing from northeast to southwest,and in the southern part of the built area,the water body and the plain vegetation area is higher than that in the northern mountainous vegetation area.The AOD of the mixed area of the central mountain vegetation and the built area is in the first two between.At the same time,the day's meteorological factors on the Aerosol Optical Depth value is also great.And the AOD is generally smaller than the AOD on NASA's 3KM aerosol product,it has a higher linear corralation coefficient.(2)Statistical analysis is performance according to the air quality report data,the results show that During the study period the AQI monthly average index and PM2.5 average value were highest in March 2016,that mean the air environment is relatively turbid,and the air environment PM2.5 pollution is more obvious,it is not conducive to human health.It is found that PM2.5 pollution in Guangzhou is mainly in the spring and autumn.And the trend of AQI index and PM2.5 concentration are very similar.(3)The air quality analysis of 51 ground monitoring stations in Guangzhou City showed that the AQI index and PM2.5 concentration of each monitoring site were in good condition during the study period,but the daily values of each site were different larger.The average PM2.5 reading in March was the highest,while June was the lowest,and the difference between the high and low value.(4)The correlation between the AOD value of Guangzhou and the PM2.5monitoring value of MODIS inversion is 0.679.At the same time significant(bilateral)of 0.000<0.01,passed the correlation test,Therefore,setting up observation and forecasting system of PM2.5 by using MODIS data to retrieve Aerosol Optical Depth is scientific and feasible.According to the observation data and the inversion results,establish the regression model of Aerosol Optical Depth and PM2.5 concentration value from linear function,logarithmic function,two times function,three times function,power function,exponential function and so on.By comparing fitting results,related parameters and test accuracy,we will find that a cubic equation function has the best fitting effect,R square is equal to 0.484,and the inspection accuracy is equal to 56.2%,that means function has a good explanation.(5)The aerosol elevation and relative humidity were corrected for the data of the two sites of the Gongyuan front station and the Liwan Fangcun station.The results showed that the two revisions improved the correlation between AOD and PM2.5concentration on the ground.