On some possibilities of multi-frequency remote sensing of the water surface

Abstract

This study is aimed at expanding the number of measured parameters to analyze the features of the formation of surface waves under the influence of wind. The paper develops an original approach to obtaining information on the variability of the short-wavelength part of the wave spectrum (examples are given for wavelengths from about 50 cm to 2 cm in 6 intervals) and the long-wave component of the wave spectrum (> 1 m) in marine conditions. Retrievable information about waves will allow studying the interaction of wind simultaneously with the short-wave and long-wave components of the wave spectrum and will be in demand by scientists involved in numerical modeling of the wave climate and interested in refining the model of near-surface wind interaction with waves. In addition, new information about the short-wave part of the wave spectrum in different wavelength ranges will improve the accuracy of near-surface wind speed retrieval from remote sensing data. This work is devoted to a theoretical analysis of slope variance retrieved from reflected acoustic pulses for different radiation frequencies depending on the near-surface wind speed and swell wave height. A study was made of the measured slope variances of large-scale waves, compared to the radiation wavelength, in six intervals depending on the wind speed and swell height. It is shown that the use of difference slope variances of the large-scale wave makes it possible to get rid of the influence of swell in the case of mixed waves and obtain a better correlation with the wind speed. A method is proposed for retrieving the declination degree for the spectrum of wave heights in given intervals of radiation wavelengths. Within the framework of this method, it is possible to retrieve the boundary wave numbers for each radiation wavelength.