Research On Wheat Condition And Growth Monitoring Based On Compact Polarimetric SAR

As the foundation of our economy,agriculture has great influence on the steady development of national and global economy.In order to meet the needs of times,our country make more efforts on the investment and support in agriculture field,precision monitoring of agricultural state can guarantee the food security of our country,turning agriculture from traditional way to information,precision and modernization,The development of remote sensing technology provides a means for crop growth monitoring in a wide range,but optical remote sensing can be easily influenced by the objective conditions during the monitoring process as result of poor data efficiency.Because of penetration,Synthetic Aperture Radar(SAR)remote sensing technology is an effective observation of earth without weather conditions influence,and sensitive to the structure and water of crop.So Synthetic Aperture Radar has an unique advantage in agricultural monitoring.Nowadays,Synthetic Aperture Radar remote sensing is widely used in agricultural field,but agricultural application research based on Compact Polarimetric SAR is seldom reported.In this paper,Qualitative study of wheat lodging monitoring based on Compact Polarimetric SAR and quantitative study of wheat biomass monitoring based on full polarimetric SAR is completed.(1)Taking wheat as the research object and farm in Eergu'Na city of the Inner Mongolia Autonomous Region Shangkuli as the study area,following works are finished:5 phases of Radarsat-2 radar data and synchronization ground lodging data were collected,compact Polarimetric SAR data simulation and polar decomposition based on Polarimetric SAR data processing theory were completed.With the combination of Compact Polarimetric SAR data and lodging data in lodging model was built and tested,Backscattering characteristics of lodging response of compact Polarimetric SAR in the qualitative aspects.(2)2 phases of Radarsat-2 radar data and synchronization wheat biomass data were collected,polarization parameters of the radar image after processing were extracted and inversion of wheat biomass model "water cloud model" were built combined with wheat biomass,Radar Polarization Characteristics response of biomass is analyzed.quantitative analysis of the radar polarization characteristics of the response of biomass,and compared with the the results of empirical model inversion.The result are as follows:(1)In heading and filling stage of wheat,the linear polarization uL of the plots without lodging is significantly lower than the plots with lodging wheat,and the linear polarization degree pL and polarization of Dop of the plots without lodging are decreased in a certain degree.When threshold value are 1.8,0.3 and 0.4,lodging can be distinguished obviously,the rest of polarization parameters can also be used in monitoring lodging,but the result shows lower effect significant reduction,so the compact polarization SAR can be used as a means of lodging monitoring of wheat?(2)The backscattering coefficient of SAR polarization parameters HH,HV,VH,VV,Lambda,Vol increased by about 5dB in filling stage and decreased by about lOdB in mature period.The experiments show that response of Polarimetric SAR backscattering coefficient of wheat stem biomass is obvious significantly.Using water cloud model and empirical model to inverse wheat biomass,the R2 of HH of July 18th and August 11th is 0.6414 and 0.8426.Results show that inversion based on water cloud model can achieve the same effect in wheat biomass inversion,and prove that water cloud model can be used in crop biomass inversion in large scale.