Research on SAR imaging mechanism for ocean wave propagating in azimuth direction by using numerical simulation

摘要

The SAR image simulation has been developed in the time domain to investigate a SAR imaging mechanism for moving ocean surfaces. In the previous paper [2], the simulation had carried out for ocean waves to confirm image displacements caused by moving surfaces. The results of the previous paper showed that the wave pattern of the azimuth wave is not displayed in the simulated SAR image. We had concluded that it is caused by velocity bunching. However, in this paper, the SAR imaging mechanism of ocean waves is reconsidered that it is affected not only by motion induced modulation but also by scattering intensity. To examine the SAR imaging mechanism, azimuth signals from moving and stationary waves are simulated. The results show that the velocity bunching might not occur in accordance with the conventional theories. It is suggested that when backscattering intensities from ocean surfaces that have radial velocities are weak, their modulations are also minor components in SAR signals. A possible explanation about diminishing wave patterns of azimuth waves in SAR images is discussed in terms of local incident angles that are angles between SAR and ocean surface.