Research On Key Technologies Of Geosynchronous SAR Imaging Simulation Of Sea Ice

Sea ice plays an important role in the global climate system,affecting the global climate by influencing the ocean thermohaline circulation and the material,energy and radiation balance of the ocean surface.Synthetic Aperture Radar(SAR)has the capability of all-day and al-weather operation,and can obtain observation data of large areas in real time,thus becoming an important means of sea ice monitoring.At present,China is carrying out pre-research on Geosynchronous Synthetic Aperture Radar(GEO SAR).As part of this work,this paper studies the key technologies for sea ice imaging simulation in GEO SAR.The main research contents of this paper are as follows:(1)The characteristics of GEO SAR system are studied.According to the spatial geometry of GEO SAR,the motion characteristics of GEO SAR are analyzed.The expressions of fourthorder Doppler parameters of GEO SAR are derived and the Doppler characteristics of GEO SAR are studied by simulation.(2)The signal model and imaging algorithms for GEO SAR are presented.Considering the "stop-go" hypothesis error,an accurate distance model suitable for the curve trajectory is established,so as to establish an accurate GEO SAR echo signal model.Based on this model,the 2-d spectrum of GEO SAR signal is derived,and the time-domain and frequency-domain imaging algorithms for GEO SAR are given.(3)Researches on GEO SAR imaging simulation of sea ice are carried out.The rough surface of sea ice is simulated by Monte Carlo method.According to the electromagnetic scattering model of sea ice,the electromagnetic scattering characteristics of sea ice are studied.That the polarization ratio can be used to distinguish sea ice from sea water is proved.Based on sea ice geometric model,sea ice electromagnetic scattering model,small surface element model and GEO SAR echo signal model,the sea ice imaging simulation algorithm of GEO SAR is established,and the reliability of the algorithm is verified by simulation.