Retrieval Of Leaf Water Content In Canopy Of Changchun Jingyuetan Vegetation Based On Remote Sensing

The water cycle is an important part of the ecosystem,and the vegetation canopy water content is an important part of it.The study of vegetation canopy water content is of great significance for monitoring vegetation growth,drought monitoring,forest fire warning and ecological security assessment.In this paper,Sentinel-1A data,Landsat8 OLI data and surface data were used to measure vegetation canopy water content,surfece roughness and surface water content data.The vegetation canopy water content of Changchun Jingyuetan National Forest Park was combined with Landsat8 OLI and Sentinel-1 A data.The exponential method was used to invert the vegetation canopy water content in the study area,and the semi-coupling empirical model based on the water cloud model using Sentinel-1 A,surface roughness and surface moisture content data was used to invert the vegetation canopy water content in the Jingyuetan area of Changchun.The main research results are as follows:(1)This paper analyzes the correlation between NDVI,NDM3,RVI and other vegetation indices and vegetation canopy water content.The principal component VSI was extracted by using three closely related vegetation indices such as NDVI,NDMI and SARI3,and participated as a vegetation index in regression model modeling.A linear regression model,an exponential regression model and a binary linear regression model were established for each vegetation index and vegetation canopy water content.After comparison,the model fit between NDVI-NDMI and vegetation canopy water content was the highest,and the adjusted complex coefficient of binary linear regression model was 0.878.(2)In this paper,a semi-coupling empirical model was established by using Sentinel-1A data eombined with field eanopy water content,surface roughness,surface moisture content,and canopy closure obtained from field surveys.Combined with the canopy closure information,the model is analyzed and improved and simplified,and the vegetation canopy water content inversion Uf Jingyuetan is realized.The results show that the R2 If the inversion canopy moisture model established by the VH polarization data was higher than the VW polarization data to establish the inversion model The VV polarization data of surface backscattering in total backscattering is larger than the VH polarization data;the higher the canopy degree is,the smaller the influence of surface backscattering is.The goodness of model inversion results was 0.859 when the canopy density was 0.8-0.9.The model was simplified by Taylor expansion,and the inversion models R2 of VH polarization data and VV polarization data were 0.8603 and 0.8265,respectively.