A speckle noise suppression method based on surface waves investigation and monitoring data

The internal energy distribution of waves can be described using ocean-wave spectra. In many ways, obtaining wave spectra on a global scale is critical. Surface waves investigation and monitoring onboard the Chinese-French oceanography satellite is the first space-borne instrument for detecting wave spectra specially, which was launched on October 29, 2018. It can avoid the shortage of synthetic aperture radar detection results while still having some problems, especially with the effects of speckle noise. In this study, a method to suppress the speckle noise is proposed. First, the empirical formula for background speckle noise is established. Second, many spatio-temporal representative fluctuation spectra are classified and averaged. Third, rational transfer function filtering is used to obtain speckle noise close to the along-track direction. Finally, a signal-to-noise ratio threshold is used to suppress the abnormal speckle noise. This method solves the problems existing in previous denoising methods, such as excessive denoising in the along-track direction and the inability of some abnormal noises to be denoised in the two-dimensional directional wave spectra.