| Marine aerosol plays a crucial role in the climate effects,while Aerosol Optical Depth(AOD),as one of the aerosol's important parameters,can not only monitor the turbidity of atmosphere above the sea,but also be an important indicator of atmospheric correction quality in water color remote sensing.Under the influence of surroundings,AOD above the Bohai Sea and Yellow Sea has the complex and variable optical properties.However,relevant studies are quite few.In addition,although there are many satellite sensors can provide remote sensing AOD products,their accuracy and effectiveness still need to be verified,which hinders our comprehensive understanding of AOD spatial and temporal distribution over Bohai Sea and Yellow Sea.For the above problems,this paper carried out the analysis of remote sensing AOD products and their spatial and temporal distributions in Bohai Sea and Yellow Sea,for the purpose of providing important scientific materials for environmental monitoring of the atmosphere over Bohai Sea and Yellow Sea and the quality of ocean color sensors' atmospheric correction.We collected filed measurements of AOD in the Bohai Sea and Yellow Sea from 2015 to 2017,to test the accuracy of remote sensing AOD products of Moderate Resolution Imaging Spectroradiometer(MODIS),Visible Infrared Imaging Radiometer Suite(VIIRS),Advanced Himawari Imager Himawari-8(AHI H8)and Geostationary Ocean Color Imager(GOCI).Meanwhile,we also took the cross validation among different sensors' AOD products.Results show that: GOCI AOD product has the highest accuracy,whose R,RMSE,MAPE and Within EE were 0.94,0.09,27.19% and 67.70%,respectively.Compared to GOCI AOD,MODIS AOD has the best correlativity,VIIRS AOD has a sparking discrete phenomenon when AOD < 0.5,as the set of band of AHI H8 and GOCI are different from other,AHI H8 AOD is larger than GOCI AOD in general.Based on the error source analysis of AOD remote sensing products found that: for MODIS and VIIRS AOD,there was a systematic overestimation in the turbid waters,while AHI H8 and GOCI AOD didn't reveal this phenomenon,these results may due to the accuracy of the calculation of surface reflectance(RS).In addition to the turbidity degree of the underlying waters,the reasonability of the chosen of aerosol models is also one of the factors affects the accuracy of remote sensing AOD products.Apart from the verification of AOD remote sensing products,this paper also tried the Simplified Aerosol Rertrieval Algorithm(SARA).However,the accuracy verification results show that SARA algorithm has regional limitations,so the algorithm still needs to be further improved to expand its spatial application.After verifying the accuracy of AOD remote sensing products,this paper analyzes the spatial and temporal distribution characteristics of AOD over Bohai Sea and Yellow Sea.Based on the comparison,it was found that AHI H8 and GOCI had basically the same spatial and temporal distribution trend of AOD,while the retrieval results of MODIS AOD and VIIRS AOD were similar with each other,however,GOCI and MODIS AOD were different in different scales of time and space.The hourly AOD maps shows that there is no obvious diurnal variation rule of AOD over the Bohai Sea and Yellow Sea.The average monthly distribution of AOD in GOCI shows that AOD in the atmosphere above the study area presented a gradual decreasing trend from the coast of China to the central and eastern part of the sea.Besides,the average monthly variation trend of AOD in the Bohai sea and Bohai strait was consistent: the highest in summer,followed by spring,and the AOD value in autumn was higher than that in winter,a little different from it,the monthly average AOD changes in the western and central parts of the Yellow sea showed that the AOD in winter was no longer the smallest.The main trend in the east and south of the Yellow Sea is that the AOD peak value in summer was no longer obvious,while the AOD value in spring was increased,and the AOD value in winter was obviously greater than that in autumn. |
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