Alexey Ermoshkin

Institute of Applied Physics, Nizhniy Novgorod, Russian Federation · Geophysical research

This paper is devoted to a series of the first field subsatellite experiments conducted in the waters of the Kuibyshev Reservoir (Kama estuary) in 2023. Simultaneously with ship-based measurements of current and wind fields, as well as chlorophyll-a concentration, two high-spatial-resolution satellite scanners surveyed the study area of the reservo...

The key area of the Arctic Ocean for atmospheric venting of CH4 is the East Siberian Arctic Shelf (ESAS). Leakage of methane through shallow ESAS waters needs to be considered in interactions between the biogeosphere and a warming Arctic climate. The development of remote sensing techniques for gas seepage detection and mapping is crucially needed...

The results of a field experiment devoted to observing slick-band shape variations occurring due to the action of heterogeneous currents related to the passage of internal waves are presented and analyzed on the basis of numerical simulation. The spatiotemporal structure of a train of five solitons of internal waves has been retrieved. Their evolut...

Narrowband spectra of sound scattered on the surface wave in the frequency range from 500 to 3000 Hz have been analyzed. Experimental results and theoretical models are reviewed. Previously published work by the authors is reviewed and new results are presented. The first characteristic case considered is forward scattering, where the sound transmi...

This paper is devoted to an acoustical method of measuring mesoscale sea and ocean currents. Due to the fact that such currents exhibit variability, long-term studies are of great interest. The aim of this study is to prepare a physical foundation to organize current measurements in an automated way using stationary mounted underwater echosounding...

Underwater acoustic echosounding for surface roughness parameters retrieval is studied in a frequency band that is relatively new for such purposes. During the described 2-weeks sea experiment, 1–3 kHz tonal pulses were emitted from an oceanographic platform, located on the northern Black Sea shelf. Doppler spectra of the resulting reverberation we...

New data was obtained for a frequency band that had not been so well-studied for sea surface probing applications before. During the described 2-weeks sea experiment 1-3 kHz tonal pulses were emitted from a platform, located on the northern Black Sea shelf, and Doppler spectrum of reverberation was studied. We believe that this band is worth furthe...

Every year situation when theArctic seas are free of ice is becoming more frequent. It allows scientists to study hard-to-reach areas using well-equipped research vessels instead of icebreakers. During the COVID-19 pandemic, the successful expedition of the research vessel “Academician Mstislav Keldysh” with more than 60 scientists from 15 countrie...

The paper presents the first results on the development of an automated high-resolution remote radar system for monitoring water areas "Ecoradar" for the purpose of automatic detection of film pollution on a wavy water surface. The complex is based on digital coherent panoramic radar manufactured by «Micran» Tomsk, operating in the X band on horizo...

We propose a laser optoacoustic method for the complex characterization of crude oil pollution of the water surface by the thickness of the layer, the speed of sound, the coefficient of optical absorption, and the temperature dependence of the Grüneisen parameter. Using a 532 nm pulsed laser and a 1–100 MHz ultra-wideband ultrasonic antenna, we hav...

The paper proposes a methodology for determining the speed and direction of the sea surface current from measurements of Doppler radar panoramas with an X-band Doppler radar. Numerical simulation of the Doppler velocity of the Bragg waves in the field of wind waves and currents were carried out. The range of distance was selected for measuring th...

The study of the microwave scattering mechanisms of the sea surface is extremely important for the development of radar sensing methods. Some time ago, Bragg (resonance) scattering of electromagnetic waves from the sea surface was proposed as the main mechanism of radar backscattering at moderate incidence angles of microwaves. However, it has been...

The paper considers the results of a promising method for remote determination of parameters of dynamic processes in the ocean-coherent ocean radar sensing. This work proposes a methodology for determining the speed and direction of the sea surface current and wind waves spectrum by measurements of X-band Doppler radar. Based on the Doppler Effect,...

The article deals with the morphological features of spreading films of surfactants on the surface of the reservoir on the basis of experiments on the Gorky reservoir under various meteorological conditions. The test substances were: oleic acid, vegetable oil, diesel. The registration of film contamination was carried out using X-band digital coher...

The article considers the issue of creating a system of environmental monitoring of film pollutions in the Gorky reservoir. A combination of the well-known model approach for calculating the drift trajectories of passive particles on the sea surface with the data of remote sensing, which provide primary detection of a spill of pollutants in the sca...

Surfactant films on the sea surface are an indicator of the processes representing the environmental threat to water bodies and coastal areas. In particular, oil spilling from accidents with oil platforms, tankers and vessel bunkering operations is of great concern. For quantitative assessment of possible damage and development of measures to preve...

This paper describes the results of the field experiment to study the effect of formation of a film slick as a result of gas escaping from the water column and shows the possibility of its detection by radar means of remote sensing. The experiment in the water area of the Gorky reservoir (Russia) using X-band radar Micran MRS-1000 installed on the...

It is known that films on the sea surface can appear due to ship pollution, river and collector drains, as well as natural biological processes. Marine film slicks can indicate various geophysical processes in the upper layer of the ocean and in the atmosphere. In particular, slick signatures in SAR-imagery of the sea surface at low and moderate wi...

The paper deals with experimental determination of the wind-driven wave spectrum by using the remote method of high-resolution coherent radar sensing of the water surface. The method is applied to the conditions of the fetch-limited wind wave growth, which is typical for enclosed waters and the sea nearshore, where the dominant wavelength is of the...

Investigation of microwave scattering mechanisms is extremely important for developing methods for ocean remote sensing. Recent studies have shown that a common two-scale scattering model accounting for resonance (Bragg) scattering has some drawbacks, in particular it often overestimates the vertical-to-horizontal polarization radar return ratio an...

The study of the movement of film pollutions (slicks) on the surface of water bodies is of particular interest for ensuring the environmental safety of intensive navigation areas, primarily the sea coastal zones and inland waterways. Diagnostics of pollution at the early stages and their quick monitoring can significantly reduce the cost of elimina...

It is well known that film slicks on the sea surface can reflect various geophysical processes in the upper layer of the ocean and in the atmosphere. Banded slick structures that appear on SAR images of the sea surface at low and moderate wind speeds are usually associated with sea currents. This paper presents the results of the first experiments...

This paper describes the construction of geophysical model function (GMF) for wind speed and surface stress retrieval at high winds from cross-polarized radar backscatter at the water surface. The starting point is the laboratory experiment designed for the study of X-band backscattering from water surface. In particular, it was shown that cross-po...

This paper is a brief review of the results of an approximate description of the evolution and interaction of composite solitons, obtained by the authors in 2001–2016. As one of the applications of the theory, the features of the evolution of intense internal waves in the shelf zone of the ocean are analyzed.

Results of the work on remote monitoring of sea surface state in the Taman Bay using X-band incoherent navigation radar FURUNO 1715 in 2009–2011 are presented. The Taman Bay is characterized by a short wave fetch and typical wave heights less than 1 m, when radar spectral methods for restoring the wave height fail to work. Therefore, regarding the...

Analysis of observations of comb structures formed at the edges of marine slicks using satellite radar imagery and data of field experiments with artificial slicks carried out from an Oceanographic Platform on the Black Sea has been performed. It is shown that the structures appear at upwind boundaries of slicks and are typical both for mineral oil...

The paper describes an experimental model of continuous wave X-band Doppler radar scatterometer (sine frequency modulation) designed for physics investigation of radio waves scattering from sea surface in controlled conditions. The prototype is developed and fabricated at the IAP RAS. Its main feature is adaptation to the conditions of a laboratory...

A new effect has been discovered in the field experiments at the Gorky Water Reservoir. The effect consists in stopping of film spreading over water surface followed by compression of the film and transition to a steady state. The evolution of a spot of a surfactant film with pre-measured characteristics was studied. The observations were carried o...

A experiments were performed in the shelf zone of the Black Sea in 2015 to study variability of the current fields and other characteristics of sea bulk, wind waves, and the near-surface atmospheric layer. Region with the secluded underwater hill streamlined with currents was selected. Measurements were carried out from the onboard of vessels on mo...

Within the framework of an approximate approach based on the representation of the Gardnerequation solitons as compound structures (different-polarity kinks), the non-quasistationary evolution of such solitary waves, which is stipulated by the variable quadratic-nonlinearity parameter α. The structure of the composite soliton is studied in cases th...

This paper presents data of laboratory experiments on a high-speed wind-wave flume of the Institute of Applied Physics (Nizhny Novgorod, Russian Federation), which are devoted to the investigation of the X-band co-polarized and de-polarized radar return in a wide range of high wind speeds (from 8 to 40 m s–1). Microwave measurements were accompanie...

Laboratory experiments directed to investigation of dependencies of the X-band normalized co-polarized and de-polarized radar cross-section on wind speed (U10) and incident angle (θ) are presented. Microwave measurements were accompanied by the measurements of air-flow (friction velocity) and wave field parameters (spectra and slope probability den...

On the basis of laboratory experiments on simultaneous measurements of normalized X-band radar cross-section (NRCS) of water surface for co-polarized and de-polarized radar return and parameters of the turbulent boundary air layer for storm and hurricane conditions, and a comparison with the available in-situ measurements, we propose a geophysical...

A experimental laboratory study of the effect of a horizontally inhomogeneous current on breaking statistics of wind waves was carried out. Were creating a current having the same direction as wind waves with positive and negative gradients and a current of the counter direction with a negative gradient. The wind speed varied from 10.4 to 20.1 m/s...

Internal waves' kinematic characteristics depend strongly on the vertical structure of the upper ocean layer's density. In this paper, the results of the hydrophysical fields' character-istics' measurements calculated from the CTD-data obtained in the 36 cruise of the " Akademik Sergey Vavilov " research vessel in October–November 2012 are presente...

The paper presents the results of experimental studies of appearance and temporal dynamics of surface-active substances (surfactants) on radar panoramas of wavy water surface carried out at the Gorky reservoir of the Volga River. Marine navigation radar operating in X-band at horizontal polarization radiation was used. Spilling alcohol solution of...

The work is devoted to the development of an empirical model of radar backscattering cross section of the ocean surface at grazing angles. Simulation results based on the composite scattering model taking into account the effect of breaking waves demonstrated a good agreement with experimental data obtained using non-coherent marine X-band radar on...

At present time radar methods of the seas and oceans diagnostics are actively developing. Using of the radar stations based on satellites and planes allows to receive information on a sea surface and a atmosphere near-surface layer with coverage of big water surface areas independently of day time. The developed methods of satellite radio images pr...

Laboratory experiments directed to investigation of co-polarized and de-polarized X-band microwave radar return from the water surface at strong and hurricane wind were carried out in the high-speed wind-wave flume. Microwave measurements were accompanied by the measurements of air-flow and wave field parameters. Experiments showed that alternative...

Both the modulation of short wind wave breaking in the long surface wave field and the occurrence of breaking in the presence of a long wave were investigated in wind-wave tank. Short wind waves were generated by the air flow at various speeds, the long surface wave at various frequency and amplitude were generated by wave maker. Data of X- and Ka-...

Both the modulation of short wind wave breaking in the long surface wave field and the occurrence of breaking in the presence of a long wave were investigated in wind-wave tank. Short wind waves were generated by the air flow at various speeds, the long surface wave at various frequency and amplitude were generated by wave maker. Data of X- and Ka-...

Laboratory modeling of depolarized radar return at strong and hurricane winds Troitskaya Yu, Abramov V, Ermoshkin A, Zuikova E., Kazakov V., Sergeev, D., Bogatov N. The accuracy of modeling and operational forecasting of storm events strongly depends on quality of data. The prevailing methods of monitoring wind speeds and directions over sea surfac...

Non-quasistationary evolution of the nearly limiting Gardner-equation solitons, which is caused by the variable parameters of the medium is considered. The proposed approximate description of such a process is based on representing the Gardner-equation solitons as compound formations formed by different-polarity kinks. The equations describing evol...

Complex experiments were performed in the north-eastern part of the Black Sea and in the south-eastern part of the White Sea to study variability of the current fields and other characteristics of the sea, wind waves, and parameters of the near-surface atmospheric layer. Measurements were carried out from the onboard of the scientific research vess...

The full-scale investigations of the action of internal waves and inhomogeneous currents on the wind waves and the near-water layer of the atmosphere were carried out in the White Sea in 2009 - 2011 yr. Measurements were carried out from onboard of the scientific research vessel "Ekolog" by optical, radar and acoustic equipment. Hydrometeorological...

Nautical X-band radar (low-cost option with the antenna beamwidth 1:9o) was applied for monitoring surface near-shore currents in the Black Sea Field Research Facility of the Southern Branch of P.P. Shirshov Institute of Oceanology. The radar signal was processed by an algorithm based on the Nieto-Borge approach. The experimental setup is shown to...

Complex ground-truth experiments were carried out in the north-eastern part of the Black Sea for several years. The main goal of the study was to record possible manifestations of nonuniform flows on the sea surface. In the experiments, we employed shipboard-type radar stations (RS) Icom and Furuno of the X range and HH polarization, radio scattero...

In this study we present the results of data processing from the 2004 Gelendzhik Bay expedition on the Akvanavt research vessel. The data were processed using the method of wavelet analysis. We found an emerging kilometer-scale variation in the surface heaving and near-water wave over the shelf area. This effect was shown to be possibly caused by t...

Space-time variability of current field characteristics, surface waves, and parameters of the near-surface atmospheric layer above the shelf zone of the Black Sea in the Gelendzhik-city region are studied. A joint analysis of the field measurement data obtained on August, 2007, September, 2008 and of the synchronous SAR images made by the Envisat s...

The results of field experiments carried out in 2007, 2008 in a north-east part of the Black sea in region of city Gelendzhik, are given. Experiments targeted the development of a bottom topography remote (radar and optical) diagnostics. Experimental area is characterized by abrupt depth dumping (fall 50 - 1250 m), and irregularity of a bank vault...

The relationship between the intensity of surface wind waves and near-water wind is analyzed. The data of measuring wind waves and near-water wind under natural conditions in the Black Sea (July 2004) and Norwegian Sea (June 2003, 16th cruise of the R/V Akademik Sergei Vavilov) are used. A phenomenon of negative correlations has been found between...