The Comparative Study Of Different Methods To Inverse Aerosol Optical Depth Based On The MODIS Data By 6S Model

Aerosol plays an important role to affect atmospheric characteristics,the variation of aerosol seriously impacts the climate and environment.The aerosol optical depth(AOD)is a main physical parameter to describe the aerosol characteristic,and it can also response the atmosphere pollution degree.In recent years,with the acceleration of urbanization industrialization process,people pay more and more attention to environmental issues.The method to obtain the AOD is becoming an interesting topic among the scholars today.We can exactly obtain the AOD above the ground station by directly observing,but because of the limit of space and time,we can't get the aerosol observing result in a whole area.So how to use the satellite data to get a large area AOD result fast,exactly and cheaply has become a hot study topic.At the end of last century,many countries in the world carried a EOS plan to send a series of satellites into the space and observe the earth successfully,using the data obtained by MODIS sensor which is equipped on the satellite to inverse the AOD has the advantages of high efficiency,wide coverage,convenience and so on,at the same time it can offer a method to monitor the air constantly.In this paper using the program compiled by IDL language and based on the 6S model,I inverse the AOD in Beijing and Liaoning areas for several days which are randomly selected in2015 by the Dense Dark Vegetation(DDV)algorithm,the Extended Dense Dark Vegetation algorithm and the Version 5.2(V5.2)algorithm as theoretical bases for studying.and with the help of the Arcgis software shows the result of inversion.The result shows that the AOD over Beijing and Liaoning areas inverted by the Dense Dark Vegetation algorithm,the Extended Dense Dark Vegetation algorithm,and the V5.2 algorithm has a good applicability,among the results of the different methods,the Dense Dark Vegetation and Extended Dense Dark Vegetation algorithms are easier and quicker,but the deviation is larger;the V5.2 algorithm needs more time but the result is more exact.In order to compare the inversion results,we can use the data observed by AERONET as standard,the average deviation of the Dense Dark Vegetation algorithm and the Extended Dense Dark Vegetation algorithm is 0.168,while the average deviation of the V5.2algorithm is 0.146,and the result of correlation analysis shows that the correlation coefficient of the Dense Dark Vegetation algorithm and the Extended Dense Dark Vegetation algorithm is0.810,the correlation coefficient of the V5.2 algorithm is 0.837.Thus it can be seen that the resultof the inversion has a reference value to the environmental protection department and the meteorological department,it can also provide an effective reference to prevent gray skies and air pollution.