Numerical simulation and validation of ocean waves measured by an Along-Track Interferometric Synthetic Aperture Radar

摘要

A new nonlinear integral transform of ocean wave spectra into Along-Track Interferometric Synthetic Aperture Radar (ATI-SAR) image spectra is described.ATI-SAR phase image spectra are calculated for various sea states and radar configurations based on the nonlinear integral transform.The numerical simulations show that the slant range to velocity ratio (R/V),significant wave height to ocean wavelength ratio (H_s/lambda),the baseline (2B) and incident angle (theta) affect ATI-SAR imaging.The ATI-SAR imaging theory is validated by means of Two X-band,HH-polarized ATI-SAR phase images of ocean waves and eight C-band,HH-polarized ATI-SAR phase image spectra of ocean waves.It is shown that ATI-SAR phase image spectra are in agreement with those calculated by forward mapping in situ directional wave spectra collected simultaneously with available ATI-SAR observations.ATI-SAR spectral correlation coefficients between observed and simulated are greater than 0.6 and are not sensitive to the degree of nonlinearity.However,the ATI-SAR phase image spectral turns towards the range direction,even if the real ocean wave direction is 30 .It is also shown that the ATI-SAR imaging mechanism is significantly affected by the degree of velocity bunching nonlinearity,especially for high values of R/V and H_s/lambda.