Sovremennye problemy distantsionnogo zondirovaniya Zemli iz kosmosa, 2020, Vol. 17, No. 2, pp. 192-198
Physical limitations of bathymetry measurement accuracy from optical images of the sea surface
1 Marine Hydrophysical Institute RAS, Sevastopol, Russia
Accepted: 18.03.2020
DOI: 10.21046/2070-7401-2020-17-2-192-198
The physical limitations of the method of estimating sea depth from a pair of optical satellite images of the sea surface obtained with a time shift that is less than the period of the observed waves are considered. The method is based on the dependence of the phase velocity of surface waves on sea depth. It is shown that estimates of phase velocities in the coastal zone can be distorted as a result of reflection from the bottom slope and underwater obstacles. In cross-spectral analysis of two images, the reflected waves change the phase spectrum and, as a result, the calculated values of the phase velocities change. Depending on the amount of time shift between images, the reflected waves can lead to both an increase and a decrease in the calculated values of the phase velocities. The greatest errors in determining the phase velocity are observed in a situation when a wave travels a distance of less than 0.2 of its length over an interval equal to a time shift between images. In the presence of reflected waves, deviations of the phase velocity values calculated from optical images from theoretical values lead to the fact that different depths can correspond to the same phase velocity value.
Keywords: bathymetry, optical satellite images, cross-spectral analysis, reflection of sea waves, dispersion ratio
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