Stereo imagery of the sea surface is one of the most effective tools for remote sensing wind waves with lengths of half a meter or more. In this paper, we propose a new method for using a series of stereo images to reconstruct the wind ripple velocity field on a long surface wave profile. The presented method is based on detecting characteristic structures on the sea surface (short wind waves, breaking waves, foam, etc.), determining their displacement between two adjacent frames (similarly to the Particle Imaging Velocimetry - PIV method), and recalculating estimated displacement from frame coordinates into three-dimensional world coordinates through projection onto a long wave profile obtained using stereo pairs. The test results on the data of stereo imagery of the sea surface carried out from a stationary oceanographic platform in the Black Sea in 2021 are presented in this paper too.

The article examines the accuracy of atmospheric correction (AC) algorithms of Sentinel-3/OLCI images of the Gorky reservoir, whose waters are characterized by a high content of phytoplankton and dissolved organic matter. All considered algorithms showed unsatisfactory accuracy due to incorrect determination of atmospheric aerosol parameters and aerosol radiance. In pixels, where atmospheric correction algorithms overestimate the aerosol radiance, aerosol optical thickness (AOT) is 3–10 times higher than the values in the adjacent areas with more clear waters. To resolve this issue, an algorithm with a fixed AOT was proposed. The fixed AOT spectrum was determined in the area with relatively “clean water” as 5 percentile of AOT in all water pixels. The proposed algorithm allowed to retrieve remote sensing reflectance with high accuracy. The slopes of lenear regression are close to 1 and the intercepts tend to zero in nearly all spectral bands. The determination coefficients are more than 0.9; the bias, mean absolute percentage error, and root mean square error are noticeably lower than for other AC algorithms.

Observing the pollution level of the atmosphere, waters, and bottom sediments in terms of physical, chemical, and hydrobiological indicators in order to study the distribution of pollutants in time and space, assess and predict the state of the Gorky Reservoir water area is an important and urgent task. To develop a regional algorithm for determining the hydrological parameters of the reservoir using satellite data, it is necessary to carry out atmospheric correction which will have significant errors without taking into account field measurements of the main optical characteristics of atmospheric aerosol over the studied water area. The study of the atmospheric aerosol optical characteristics over the Gorky Reservoir is carried out because of in-situ measurements using the SPM photometer as well as satellite data of high spatial resolution Landsat and Sentinel. The resulting irregular data set is insufficient for a quantitative and qualitative assessment of the spatial and temporal variability of regional aerosol characteristics. The obtained seasonal results of the analysis of optical characteristics require regular monitoring and are promising and relevant for research.

The registration and processing of the sea surface images is a well-developed remote sensing instrument for estimating wind wave parameters. According to literary sources, there are many implementations of the method, mainly based on surveying the sea surface from above water, including the use of stereo systems. However, methods for restoring wave characteristics from its underwater image are also known. This paper presents the preliminary results of the first stereo observation of the sea surface from underwater when the camera is oriented to the surface at angles close to the angle of total internal reflection. In this case, waves of different scales (depending on the optical properties of water and the immersion depth of the stereo system) appear as contrast objects in the image. The presented paper analyzes the fundamental difficulties of underwater stereo imagery, indicates the advantages/disadvantages, presents the results of restoring disparity maps, and draws conclusions on the practical applicability of the proposed method.

Given paper describes preliminary results of radar remote sensing East Arctic seas during the 82ndcruise of research vessel (R/V) “Academician MstislavKeldysh“on September- November 2020. For this purpose, the coherent Panoramic radar MRS-1000 Micran operating in the X-band on HH polarization located on the highest deck was used for recording the state of the sea surfaceduring R/Vmoving anddrifting. Acorresponding method for generating high spatial resolution radar maps of the sea surface and detecting different hydrophysicalprocesses is proposed in this paper. Some examples of registered processes likewind waves, ice fields with different types of ice (grease ice, pancake ice, nilas, and young ice), manifestations of internal waves observed in the Kara Gate and Vilkitsky Strait are presented here. Doppler radar images obtained by the difference-phase method demonstrate the prospects of their use for determining the surface current velocity and the orbital velocities of wind waves.

Two aspects of the problem of marine film slicks and their remote sensing are considered. The first one is the slick evolution accounting for the action of wind waves. Results of field experiments with surfactant spills are presented and the along-wind and cross-wind axes of slicks as functions of time at different environmental conditions are discussed. A model of slick evolution taking into account surface stresses induced by wind waves is developed and is shown to be consistent with experiment. The second considered aspect of the problem is related to remote sensing of marine films using X-/C-/S-band two-polarized radar. Experiments with artificial slicks have indicated that both Bragg and non polarized scattering significantly contributes to the radar return, and the depression of radar backscatter in slicks as a function of radar wave number can be strongly different for Bragg and non polarized components.