Предложена методика использования спутниковых радиолокационных изображений Sentinel-1 для оценки затухания длинных гравитационных волн в присутствии фрагментированного ледяного покрова.Методика основана на оценке флуктуаций удельной эффективной площади рассеяния (УЭПР), связанных с модуляцией мощности радиолокационного сигнала длинными океаническими волнами.На основе концепции модуляционно передаточной функции предполагается, что малые вариации УЭПР на масштабах длинных волн пропорциональны амплитуде последних.Затухание волн определённой длины, распространяющихся в заданном направлении, оценивается по изменению их амплитуды на разных участках радиолокационного изображения, направление распространения волн определяется из анализа двумерного спектра радиолокационного изображения морской взволнованной поверхности.

The increasing amount of plastic debris in water ecosystems provides a new substrate (epiplastic microhabitats) for aquatic organisms. The majority of research about epiplastic communities has focused on seawater environments, while research is still quite limited and scattered concerning freshwater systems. In this study, we analyze the first stages of colonization on different types of plastic by a periphytic algae community (its composition and dominant species complex) in freshwater bodies located in a nature reserve (within the Middle Volga Basin). A four-week-long incubation experiment on common plastic polymers (PET, LDPE, PP, and PS), both floating and dipped (~1 m), was conducted in two hydrologically connected karst water bodies in July 2023. The composition of periphytic algae was more diverse (due to the presence of planktonic, benthic, and periphytic species) than the phytoplankton composition found in the water column, being weakly similar to it (less than 30%). Significant taxonomic diversity and the dominant role of periphytic algae were noted for diatoms (up to 60% of the total composition), cyanobacteria (up to 35%), and green (including Charophyta) algae (up to 25%). The composition and structure of periphytic algae communities were distinct between habitats (biotope specificity) but not between the types of plastic, determined primarily by a local combination of factors. Statistically significant higher values of abundance and biomass were demonstrated for some species, particularly for Oedogonium on PP and Nitzschia on LDPE (p-value ≤ 0.05). As colonization progressed, the number of species, abundance, and dominance of individual taxa increased. In hydrologically connected habitats, different starts of colonization are possible, as well as different types of primary succession (initiated by potentially toxic planktonic cyanobacteria or benthic cyanobacteria and mobile raphid diatoms). Within the transparency zone, colonization was more active on the surface (for example, in relation to green algae on PP (p-value ≤ 0.05)). These results indicate a tendency for microalgae communities to colonize actively submerged plastic materials in freshwater, and they may be useful in assessing the ecological status of these aquatic ecosystems.

This study is aimed to develop an empirical model of the spectrum of short wind waves in application to a Bragg component of microwave backscattering from the sea surface at moderate incident angles. The radar backscatter in the model is considered as a composition of Bragg (polarized) and non-Bragg (nonpolarized) components. Data of field experiments on radar probing of film slicks carried out with an X-/C-/S-bands two co-polarized radar instrument were used. An empirical expression for an additional source of Bragg centimeter-scale wind waves is proposed, which made it possible to describe the variations of radar backscatter in slicks when the latter are observed in the cross wind direction. The source is described by a power function of a dimensionless parameter-the wave age. It is shown that the additional source can be considered isotropic, as evidenced by good agreement between the measured contrasts in the upwind direction and those calculated using this model.

Sea ice in its initial formation stages in the nearshore zone can exist in various forms such as grease ice, snow sludge, and pancake ice. These initial ice forms (IIFs) lead to the attenuation of waves on the sea surface, consequently affecting the intensity of microwave scattering on the sea surface. This complicates the identification of areas covered by IIFs that are situated between consolidated ice and open water. This work aims to analyze wave propagation in the presence of IIFs to develop physical models of wave attenuation. The paper presents a description and results of special field experiments to investigate the attenuation of wind waves of various lengths in the presence of ice simulators. Results of numerical simulation of the attenuation of gravitational waves and a comparison with experimental results are also given. One of the significant findings in the studied dependence of the attenuation coefficient on the ice floe size-to-wave length ratio, observed in both field and numerical experiments, is the discovery of a local maximum for waves with lengths of the order of the “ice floe” size. A physical interpretation of the mechanism of gravitational wave attenuation in the presence of ice floes is proposed, taking into account their attached mass.

Проблема загрязнения океана пластиковым мусором (ПМ) и развития физических основ его дистанционной, в том числе радиолокационной, диагностики приобрела в последние годы исключительную важность.В настоящей статье на примере полиэтиленовых плёнок, плавающих на водной поверхности, представлены результаты первых специальных натурных экспериментов по исследованию влияния ПМ на характеристики радиолокационных сигналов микроволнового диапазона.Радиолокационное зондирование выполнено с использованием доплеровского скаттерометра Ka-диапазона, установленного на движущемся маломерном судне, при средних углах падения микроволн, на вертикальной и горизонтальной поляризации, под углом к ветру и поперёк ветра.Коэффициент затухания ветровых волн при прохождении ими области, занятой плёнкой, измерен с использованием миниатюрных акселерометров.Обнаружено значительное (в единицы -десятки раз) ослабление интенсивности радиолокационного сигнала в подветренной по отношению к плёнке

The paper is devoted to the problem of estimating marine current velocity from microwave radar data, one of the important tasks of sea remote sensing. We present some results of simultaneous measurements of radar scatterers velocities and sea current and wind velocities. Radar scatterers velocities were measured using a dual-polarized (VV/HH) Doppler radar operating in S/C/X bands. The experiments were carried out in the coastal zone of the Black Sea at moderate incidence angles (30–70 degrees). It was obtained that the subsurface current velocity (current in the upper layer of ten centimeters) retrieved from the Bragg component of the radar return can be used to estimate changes in marine current (a part of the sea current that is not related to the wind) at constant wind speed. The subsurface current velocity is found as a vector sum of the current velocity measured at a depth of 1 m and the wind component equal to 1–3% of the wind speed. Possibilities of estimating the current velocity from VV/HH/PD data are analyzed.

3 Волжский государственный университет водного транспорта Нижний Новгород

The article deals with the problems of Internet communication in relation to human life. According to the authors, Internet communications have a powerful impact on a person. The article suggests that this effect largely depends on the attitudes of the person himself. What Internet communications are for him — a goal or a means of existence — this ultimately determines the logic of human behaviour, the positive or negative nature of the communicative impact on a person. At the same time, the authors emphasize the importance of considering Internet communications as an integral part of modern human life. Internet communications are an important means of meeting people’s needs. Therefore, it is important to find a “golden mean” in the use of Internet technologies, putting under control the selection of information and the time of assimilation of it in order to make your life more comfortable and meaningful.

ФИЦ Институт прикладной физики им.А.В.Гапонова-Грехова РАН

In this paper we present the results of a laboratory experiment simulating the mechanisms of a surfactant film localization under the action of periodic surface waves. It is shown that the film compressed by a surface wave, can be conditionally divided into three sections — the dense film region as the most distant from the wave source, the area of a diluted film and the region of relatively clean water. The paper is focused on the processes occurring in the diluted film region characterized by the transition from clean water to the dense film, where horizontal circulation currents are registered. The character of currents is varying depending on the wave amplitude so that the divergent circulation cells occur at small and large wave amplitudes, but at medium amplitudes the roller currents forming a convergence zone on the basin axis are observed. The experimentally obtained stationary distribution of surfactant concentration is compared with the previously developed model of film compression due to surface tension induced by waves. The comparison shows good agreement between the theory and the experimental results at small and large wave amplitudes. Their discrepancy at medium wave amplitudes in the diluted film region is presumably related to the presence of convergent cells which are not considered in the model.

Выполнен анализ имеющихся данных спутниковых мультиспектральных наблюдений эвтрофированного водоёма на примере Горьковского вдхр., в частности в ближнем (NIR -англ.near infrared) и коротковолновом (SWIR -англ.short wave infrared) инфракрасном диапазонах, в областях интенсивного цветения фитопланктона, а также в разливах поверхностноактивных веществ (ПАВ) на водной поверхности.Для анализа использовались данные, полученные с помощью Sentinel-2 MSI (англ.Multispectral Instrument), а также сопутствующие подспутниковые наблюдения.Проанализированы спектральные контрасты для плёнок различной природы и толщины в видимом и NIR/SWIR-диапазонах. Показано, что биогенные плёнки на поверхности воды в областях интенсивного цветения фитопланктона могут быть достаточно толстыми и проявляться в виде областей плотной «корки», которые характеризуются значительными контрастами на изображениях в NIR-и SWIR-диапазонах.Тонкие биогенные плёнки, которые можно рассматривать как квазимономолекулярные, слабо проявляются в SWIR-диапазоне подобно мономолекулярным плёнкам ПАВ, чьи контрасты во всех диапазонах близки к 1. В NIR-диапазоне контрасты тонких биогенных плёнок более существенны и близки к значениям для немономолекулярных (перенасыщенных) плёнок ПАВ, при этом контрасты последних, в отличие от тонких биогенных плёнок, значительны и в SWIR-диапазоне.Указанные особенности мультиспектральных изображений биогенных плёнок могут быть использованы

Suppression of radar backscattering from the sea surface has been studied in field experiments with surfactant films carried out from an Oceanographic Platform on the Black Sea and from onboard a research vessel on the Gorky Water Reservoir using an X-C-S-band two co-polarized radar instrument. Bragg and non-polarized (non-Bragg) radar backscatter components, BC and NBC, respectively, were retrieved when measuring the radar backscatter at vertical (VV-) and horizontal (HH-) polarizations. New features of microwave backscattering from the sea surface have been revealed, including a non-monotonic dependence of radar backscatter suppression (contrasts) in slicks on azimuth angle and particularities of BC contrasts on radar wave number. Namely, it is demonstrated that the backscatter contrasts achieve maximum values at azimuth angles in between the upwind and crosswind radar look directions, and BC contrasts increase with radar wave number along the wind and decrease in the crosswind directions. The suppression of BC is discussed in the frame of Bragg's theory of microwave scattering and of a simple model of the wind wave spectrum, while the suppression of NBC is considered associated with the micro-breaking of wind waves. The obtained new features of radar contrasts can be used for the identification and characterization of marine films.

A new approach to the problem of damping of gravity–capillary waves (GCW) on water covered with a layer of viscous liquid (a film) of finite thickness with two elastic boundaries is developed. It is shown that the rotational component of GCW can be described formally as a “forced” longitudinal or Marangoni wave (MW), and the potential component of GCW plays a role of the “external force.” The resonance-like excitation of the forced MW is demonstrated when the GCW and MW frequencies and wave numbers are approximately close to each other. For a film that is thinner than the viscous boundary layers in film, a single forced MW exists that is located within the boundary layer beneath the water surface. For a thick film, the forced MW is characterized by the existence of two spatially separated MW modes: one is localized in the boundary layer below the upper, air–film interface and another within the boundary layers in the vicinity of the water–film interface. Then, at different elasticities of the interfaces, a double peak dependence of the GCW damping coefficient on wave number can occur due to the resonance with the two forced MW modes. The dependence of the damping coefficient on film thickness is characterized by a strong maximum appearing when the film and boundary layer thickness values are comparable to each other. The developed theory is consistent with existing numerical studies and experiment.

Определение скоростей и структуры поверхностных течений по данным микроволновых радиолокаторов -одна из важных проблем дистанционного зондирования морской поверхности.В статье представлены некоторые результаты измерений скоростей поверхностных течений по доплеровским спектрам, полученным поляризационным многочастотным радиолокатором (X-/C-/S-диапазоны) при умеренных углах падения излучения (40-70°) в направлении навстречу ветру и сравнение их с независимыми измерениями поверхностных течений с помощью акустического доплеровского профилографа течений (ADCP).Скорости радиолокационных рассеивателей определялись по центру тяжести доплеровского спектра (доплеровскому сдвигу) обратно рассеянного сигнала на VV-и HH-поляризациях, а затем для брэгговской (поляризованной) и небрэгговской (неполяризованной) компонент.Показано, что скорость течения, восстановленная по доплеровским сдвигам брэгговской компоненты после вычитания собственной скорости брэгговских волн, хорошо согласуется с данными независимых измерений.Для неполяризованной компоненты скорость рассеивателей близка к сумме скорости поверхностного течения и скорости дециметровых волн с длинами 10-70 см, резкое изменение скорости рассеивателей наблюдается при скоростях ветра порядка 5-7 м/с.Последнее объясняется вкладом в рассеяние неполяризованной компоненты, связанной с мелкомасштабными обрушениями, двигающимися со скоростью коротких дециметровых волн (20-30 см), и отдельными сильными обрушениями волн (пенными гребнями), двигающимися со скоростями метровых волн.При скоростях ветра, при которых на поверхности по

Nonlinearity of gravity-capillary waves (GCWs) plays an important role in the wind wave dynamics and in microwave scattering from the sea surface. This study is aimed to investigate in wave tank experiment characteristics of nonlinear features of mechanically generated centimeter-decimeter-wavelength GCW—parasitic capillary ripples (PCRs) and bulge/toe structures, and their contribution in microwave radar return. An optical method of visualization of GCW profile with high spatial resolution was developed to study GCW profile and Ka-band Doppler scatterometer was used to measure backscattering at vertical (VV) and horizontal (HH) polarizations. Dependencies of PCR slopes and bulge curvature on steepness of dm-scale GCW have been obtained and indicated sharp growth in the vicinity of the limiting steepness of order 0.3. PCR slopes and bulge curvature both decreased in the presence of film, but PCR appeared to be stronger suppressed by film than the bulges. The velocities of microwave scatterers retrieved from radar Doppler shifts were found to be consistent with the phase velocities of 4-Hz GCW, but smaller for GCW of lower frequencies. Both the phase velocities and the scatterer’s velocities slowly increased with GCW steepness. Polarization ratio (PR) values decrease with GCW steepness and in the presence of film, thus indicating the enhanced relative contribution of nonpolarized scattering for very steep GCW and when film is applied on the water surface. We consider that the aforementioned results can be explained under an assumption that PCR contributes mostly to Bragg scattering component, while bulge/toe structures contribute to nonpolarized scattering.

It is well known that marginal ice zones are characterized by different forms of initial stages of ice such as, e.g., grease and fragmented ice which act as surface wave absorbers and thus affect microwave radar backscattering. As a result, mapping of boundaries between solid ice and open water areas using radar may become rather complicated. Another aspect of the problem of wind wave damping due initial stages of ice is that the areas of strong wave damping due to ice can be erroneously interpreted as surface pollutions in radar imagery. Studies of wave damping due to ice floes are still insufficient, and relations between the floe geometry and wave damping are poorly established. The motivation of this study is to improve our understanding of the process of wave damping due to ice floes for elaboration of physical models of wave damping. New wave tank experiments were carried out to investigate the damping of regular mechanically generated waves and of irregular wind waves due to drifting floe imitators (washing sponges) as well as for the case of stationary, non moving floes. Dependencies of the damping coefficient on wave frequencies for regular and wind waves for different floe sizes and different areas occupied by the floes were obtained. One of the most interesting results was that the damping coefficient indicated a local maximum when the floe size was about half the wave length. A physical interpretation of the results was given, based on the analysis of floe movement under the action of the orbital wave motion taking into account the floe added mass.

The river confluence is one of the most complex processes in river morphology, which plays an important role in riverbed deformation, mixing processes, pollution transport, etc. The area of river confluence can be often visually observed as the relatively thin transition region or mixing zone (MZ) separating two parallel weakly mixing flows. The mixing zone characteristics, in particular width, are important indicators of the turbulent mixing intensity and momentum and substance exchange between two flows, therefore, understanding the physical mechanisms affected on the mixing zone formation and manifestation is an important task in ecological remote monitoring. A typical example of a river confluence is the merging of the Volga and Oka rivers (Russia). In this work satellite radar and optical images of the Oka -Volga MZ during the active ice cover melting were analyzed. The mixing zone of rivers as the formation of wet snow at the initial stages of melting, which further contributes to the formation of open water patches in the area of rivers confluence zone is shown. Such manifestation of the mixing zone can be presumably associated with factories / thermal power plants emissions and turbulent mixing of river flows. An increase of the radar signal backscattering of wet snow was observed, and it can be associated with the predominance of surface scattering (an increase of affection of surface roughness) with an increase of snow and ice cover moisture. In conditions of positive average daily temperatures, intense ice melting led to the appearance of open water patches, which were partially covered with fragmented ice. Although the wind velocity during the observation period was about 3-5 m/s, which significantly exceeds the threshold of wind waves excitation, the latter, was rather weak, in particular, due to the wind wave damping on the water covered with the floes. This led to the manifestation of the MZ as an extended dark band, and also presumably caused weak radar backscattering after the ice opening of the Volga part. The research was funded by the Russian Foundation for Basic Research (Projects RFBR № 18-45-520004 and № 20-05-00561)

Studies were carried out to create highly heterotic interlinear winter rye hybrids F1 based on Pampa CMS and to identify high-yielding combinations with the best grain quality. More than 350 relatively highly productive and short-stemmed inbred forms were obtained by repeated inbreeding of self-fertile plants. Analogs with sterile Pampa cytoplasm were created using 40 of the best lines by saturating backcrosses. Interline crosses were carried out and lines with high general and specific combining ability, as well as forms with complete restoration of fertility and fixing of sterility, were identified. Based on inbred lines originating from the Saratov (H-1185, H-1247) and Vyatka (H-1423, H-1432) gene pools, by crossing a simple interline hybrid F1 (cms H-1185 × mf H-1247) with a two-line synthetic C-899/20 Rf (obtained from crossing the lines Н-1423 and Н-1432), a promising commercial rye hybrid Nemchinovsky 1 was created. During the years of competitive testing (2017–2020), its average yield was 6.4 t/ha, which is 0.63 t/ha, or 10.9%, higher than for the Valdai reference. This was due to the higher number of ears per 1 m2 (by 98 pcs.). The average plant height was 136 cm, which is 3 cm lower than the reference. Due to the strong stem, the hybrid is characterized by better lodging resistance, while its winter hardiness and thousand kernel weight are comparable to those of the reference. Nemchinovsky 1 is characterized by better indicators of grain quality: it consistently outperforms the reference in terms of amylogram height (by 64 units), falling number (by 41 s), starch gelatinization temperature (by 1°C), viscosity of aqueous extract of grain meal (by 0.7 cP), and shape stability of hearth bread (by 0.04 units).