Research On The SEA Surface Current Measurement Using Spaceborne AT-InSAR Technique

The strategy role of the ocean becomes more and more important,and the information of sea surface current is vital to both military and civilian applications.The conventional SAR processing techniques can hardly extract velocity information from SAR images.However,the ATI technique provide a possible way to extract velocity information in large area in a short time with nearly full resolution of conventional SAR.We discuss the scattering mechanism of sea surface interacting with the radar electromagnetic waves,and analyze the critical factors that may influence the accuracy of sea surface velocity measurement.We carry on a systematic analysis on the Ka band AT-InSAR's ability of surface current measurement.In the meantime,considering the lack of in-situ data of AT-InSAR,we develop a spaceborne AT-InSAR raw signal simulation system aiming at exploring other ocean features like internal wave,eddies,tides etc.In specific,the main work can be concluded in the following aspects:(1)We propose the CDSC facet model to simulate the sea surface elevation,combining the sea surface characteristics with the SAR parameters.We use the deterministic facet to model the long gravity waves,and use the Bragg wave spectra to model the short waves.The combing effects can reflect both macro and micro structure of sea surface.(2)We introduce the hydrodynamic term to the scattering model,and adopt the CDSC facet model to construct the sea surface elevation model at each slow time.(3)We propose a Ka band AT-InSAR system,which afford a shorter baseline and analyze the ability of this system.The conclusions are: a).this system can achieve high resolution velocity measurement accuracy without high demand on the spatial resolution.and b).we can save many efforts in system design with a little loss in sea surface wave direction accuracy.(4)Based on the CDSC facet model,and the scattering model we proposed,we developed a spaceborne AT-InSAR raw signal simulation system,and this simulation system provide a way out of the shortness of in-situ data..