The most common models of the wind wave spectrum are reviewed, and the compliance of the studied spectra with several fundamental criteria is estimated. These criteria are the ability to simulate diverse wave climate and agreement between model‐based calculations of the mean square slope and experimental data. The spreading function of the spectrum should also correspond to the experimentally measured Doppler spectrum, while the dependence of the radar backscatter cross section should conform to geophysical model functions for various wavelength ranges of incident electromagnetic radiation at moderate incidence angles (20–60°). An analysis has shown that none of the considered spectrum models fully satisfies all the criteria; thus, a new spectrum model for wind waves was developed. Boundary wave numbers for various wavelength ranges of incident electromagnetic radiation within the framework of a two‐scale surface model were determined for the new model. The spectrum model can be used to simulate ripple attenuation in oil slicks and to calculate the radar backscatter cross section inside slick.

Improvement of methods for satellite monitoring of the world ocean state is one of the most important areas of the remote sensing because of the influence the oceans have on the Earth's climate. Currently, only one parameter is measured on a regular basis on a global scale: the significant wave height which is obtained from spaceborne radar altimeter data. It is known that at small incidence angles within the framework of Kirchhoff approximation, the backscattering radar cross section depends mainly on the mean square slope (mss) of the sea surface; therefore, this parameter can be measured. The performed studies lead to the improvement of the methods for processing the data from a precipitation radar. We demonstrate that the mss of the large‐scale (compared to the radar wavelength) sea waves can be restored within the swath, that is, about 115 km wide. The aim of this work is to communicate these new possibilities to the broad research community involved in the studies of the oceans. In this paper, a review of the results is performed and the prospects for global monitoring are first shown. On the basis of the precipitation radar data, it becomes possible to measure global fields of sea wave slopes, which in turn will help scientists to analyze the processes of air‐sea interaction. Availability of this new mss parameter essentially doubles the amount of available descriptors of sea waves, which will advance the understanding of the processes occurring in the oceans.

In the radar remote sensing of sea ice, the main informative parameter is the backscattering radar cross section (RCS), which does not always make it possible to unambiguously determine the kind of scattering surface (ice/sea waves) and therefore leads to errors in estimating the area of the ice cover. This paper provides a discussion of the possibility of using the Doppler spectrum of the reflected microwave signal to solve this problem. For the first time, a semi-empirical model of the Doppler spectrum of a radar microwave signal reflected by an ice cover was developed for a radar with a wide antenna beam mounted on a moving carrier at small incidence angles of electromagnetic waves (0°–19°). To describe the Doppler spectrum of the reflected microwave signal, the following parameters were used: shift and width of the Doppler spectrum, as well as skewness and kurtosis coefficients. Research was conducted on the influence of the main parameters of the measurement scheme (movement velocity, width of antenna beam, sounding direction, incidence angle) and the sea ice concentration (SIC) on the parameters of the Doppler spectrum. It was shown that, in order to determine the kind of scattering surface, it is necessary to use a wide or knife-like (by the incidence angle) antenna. Calculations confirmed the assumption that, when measured from a moving carrier, the Doppler spectrum is a reliable indicator of the transition from one kind of scattering surface to another. The advantage of using the coefficients of skewness and kurtosis in the analysis is that it is not necessary to keep the radar velocity unchanged during the measurement process.

This paper presents the results of field measurements of surface waves parameters obtained in the expedition to a fixed offshore platform in the Black Sea near the Katsiveli settlement in 2015. For the first time experimentally confirmed the efficiency of the new method of directly measuring the slope variances and other surface waves parameters affect the scattering of ultrasound and microwaves. The method is based on the analysis of spectral and energy characteristics of the reflected acoustic waves at underwater surface waves observation. A feature of this method is the simultaneous use of multiple antennas with different radiation patterns. The scheme of measurements with a single radiating and three receiving antennas with different radiation patterns implemented in the acoustical wave gauge manufactured in the IAP RAS. Sensing of the water surface occurs vertically, so that the scattering occurs in quasispecular area. This measurement scheme allows retrieving all the parameters of surface waves that effect on scattering cross-section, the width and the shift of Doppler spectrum of the reflected radiation. String wave gauge used in the experiments to control the effectiveness of a new method. Using of string wave gauge is a standard for precision measurements of surface waves.