Study On Turbidity Distribution In The Bohai And Yellow Sea Based On Multi-Source Satellites

Turbidity is an important parameter in water quality measurement,which is a comprehensive factor of water quality and an important index of water quality environmental monitoring.Turbidity can cause the changes in the vertical structure of water temperature,which has an important impact on Marine primary productivity,and has special significance for the study of Marine ecology and biochemical processes,hydrodynamic environment and material transport.Traditional ocean observation methods have limitations,while satellite remote sensing technology has the advantages of long time and wide range of monitoring,providing an ideal means for the dynamic change of ocean turbidity.Summary of previous research findings:there are few studies on high-turbidity water bodies,and few studies on water turbidity by using the VIIRS satellite.Therefore,this study uses Bohai and Yellow Seas as the study area.A remote sensing inversion algorithm of turbidity in the Bohai and Yellow Seas based on VIIRS satellite is established by using platform buoy and field turbidity data from voyage observation to match with the satellite in high spatio-temporal synchronization,and the accuracy of the algorithm is verified.Finally we get a stable algorithm for the turbidity of Bohai and Yellow Seas.The new algorithm is applied to MODIS and GOCI satellites to verify the applicability of the algorithm.Then the spatial and temporal distribution characteristics of turbidity in the Bohai and Yellow Seas is studied by using the new algorithm and the turbidity changes in different months,seasons and years and the typical distribution characteristics in different regions are obtained.The main research results are as follows:?1?By testing the sensitivity band of VIIRS satellite data and analyzing the spectral characteristics of remote sensing reflectivity,it is found that the most sensitive band to the turbidity signal of the Bohai and Yellow Seas is the band of 486nm;Then,different band combinations are tried,and stability tests are carried out on the algorithms of the two combinations.Finally,the model constructed by the single-band form(log₁₀R_rs?7??₃?8?)has the highest estimation accuracy,and the model's determination coefficient R² is 0.974,RMSE is16NTU,MAE is 23NTU,and MRE is 34.63%.?2?The new algorithm is applied to the sensor of MODIS and GOCI satellite to verify its applicability,and it is found that its applicability is good.The estimation accuracy effect of the three satellites is as follows:the simulation effect of MODIS and VIIRS is relatively close,followed by GOCI.?3?From the perspective of time,the turbidity of the Bohai and Yellow Seas mainly presents as:The turbidity of water increases gradually from September to December.The turbidity of water remains stable in January and march.The turbidity of water decreases gradually from April to June.Turbidity remains stable in July and August.The distribution on the seasonal scale is:the turbidity of water remains at a high level in winter,the high turbidity region shrinks gradually in spring and reaches its lowest value in summer.Only in coastal areas,turbidity is still high.In autumn,turbidity gradually increases again.For the whole study area,the turbidity value is the lowest in 2012 and the highest in 2018.?4?From the perspective of spatial distribution,the turbidity in the Bohai and Yellow Seas mainly presents as near shore high,far shore low.In the Bohai,the regions with high turbidity are mainly distributed in the estuary of the Yellow River,Bohai bay,the bottom of Liaodong bay and the shoal of Liaodong sea,while the Bohai strait and the middle of Bohai sea have low turbidity.In the Yellow sea,the areas with high turbidity are concentrated in the waters near the coast of Jiangsu and the western side of the Korean peninsula,especially in the shoal area of north Jiangsu,where turbidity is the highest and is always in the state of high turbidity.