RAW Data Simulation For Ocean Surface Elements

Synthetic Aperture Radar(SAR)and Along-Track Interferometric(ATI)extended in SAR have many advantages of full-day observation,all-weather observation,wide swath and high resolution,which can be used to obtain large areas and high resolution and high precision ocean surface information(waves,currents,etc.).The SAR sea surface raw data simulation as an important means to study how to extract ocean surface information can better help people study various physical mechanisms of SAR sea surface elements,and is also a necessary method for the design of a new Marine remote sensing spaceborne SAR system.However,there are some troubles in the simulation of SAR sea surface raw data at present.First,the ocean surface raw data simulation does not take into account the situation of radar antenna with large squint sidelooking angle,which is the key to develop of sea surface vector flow field at one time.Second,there is no perfect ATI-SAR simulation method,and ATI-SAR is one of the most promising applications of SAR at present,which needs to be further studied.Thirdly,Stokes drifting,which is very common at sea level,was not taken into account in the simulation.The basic principle of ocean surface simulation is to be as close as possible to the real sea level.Based on the current side-looking IOK simulation algorithm,this paper pushes the IOK simulation algorithm in the squint side-looking angle.Without changing the raw data sidelooking IOK algorithm,the coordinates of the squint beam center position of the zero-azimuth moment are recalculated,and the position of the SAR raw data in the Doppler domain is determined according to this to extend it to the large squint side-looking angle.Consider the IOK algorithm.The result is a good inversion of the hypothetical current field,and the accuracy meets the requirements with margin of error is within 8.5%,and the focused SAR image is a good representation of the shape of the sea wave field.Based on the side-looking sea surface raw data simulation method,the ATI-SAR simulation algorithm is derived by adding the interference phase and using small-scale spatial variation to achieve the irrelevance of the two interferograms.Then the ATI-SAR radial flow field inversion performance under different sea conditions is analyzed by simulation,which proves correctness of ATI-SAR raw data simulation.Then the simulation results show that the effect of Stokes drift on the sea surface velocity measurement will change due to the change of the angle between the large-scale wave propagation direction and the radar flight direction,and the quantitative relationship of the influence is obtained.