Measurements of ocean wave spectra with vertical polarization X-band radar image sequences

Ocean wave parameters, such as significant wave height, can be computed from wave spectrum. Ordinarily X-band nautical radar can produce the three dimensional wave number frequency image spectra from a time series of radar images with a 3-D FFT algorithm. The fundamental image spectrum is related to the surface wave spectrum by the modulation transfer function (MTF). To determine the modulation transfer function, the field experiment for vertically polarized X-band nautical radar is carried out at Zhangzi Island. This paper presents the results of an experimental study by in-situ data analysis with existing inversing modeling method aimed at estimating the vertically polarized modulation transfer function, which can minimize the difference between the image spectra from radar images and spectra from buoy, and measuring the sea parameters using ocean wave spectra for two polarizations.