Aleksey Marchenko

Long waves in shallow liquid under ice cover

Abstract Long waves in shallow liquid under ice cover which is under tension or compression are studied. An equation describing the propagation of such waves is obtained first. Exact solutions of the equation in the form of cnoidal waves and solitons are derived and studied. It is shown that in the case of sufficiently low tension and in all cases of compression the periodic waves in a shallow liquid are unstable and collapse. Waves in a liquid of finite depth under ice cover have been studied by many workers in the linear approximation (see e.g. /1, 2/). The influence of non-linearity on the propagation of periodic waves and wave packets of finite intensity was first studied in /3, 4/, where it was shown that periodic waves are unstable in a deep fluid and collapse under any compressive-tenslle loads acting on the ice cover that may be encountered in practice.

The floating behaviour of a small body acted upon by a surface wave

Abstract The passive motion of a body on the ruffled surface of a liquid acted upon by gravity and drag forces is considered. The dimensions of the body are much less than the wavelength and the oscillations of the body in a direction normal to the liquid surface are ignored. Two cases of motion, corresponding to turbulent flow around the body and gliding, are investigated.

Remote sensing of seawater and drifting ice in Svalbard fjords by compact Raman lidar

A compact Raman lidar system for remote sensing of sea and drifting ice was developed at the Wave Research Center at the Prokhorov General Physics Institute of the Russian Academy of Sciences. The developed system is based on a diode-pumped solid-state YVO(4):Nd laser combined with a compact spectrograph equipped with a gated detector. The system exhibits high sensitivity and can be used for mapping or depth profiling of different parameters within many oceanographic problems. Light weight (∼20 kg) and low power consumption (300 W) make it possible to install the device on any vehicle, including unmanned aircraft or submarine systems. The Raman lidar presented was used for study and analysis of the different influence of the open sea and glaciers on water properties in Svalbard fjords. Temperature, phytoplankton, and dissolved organic matter distributions in the seawater were studied in the Ice Fjord, Van Mijen Fjord, and Rinders Fjord. Drifting ice and seawater in the Rinders Fjord were characterized by the Raman spectroscopy and fluorescence. It was found that the Paula Glacier strongly influences the water temperature and chlorophyll distributions in the Van Mijen Fjord and Rinders Fjord. Possible applications of compact lidar systems for express monitoring of seawater in places with high concentrations of floating ice or near cold streams in the Arctic Ocean are discussed.

Interaction of short internal waves with the ice cover in an Arctic fjord

Measurements of the short internal waves in a shallow Arctic fjord revealed that the fluctuations of the temperature and current velocity with a period of approximately 10 min and the amplitude of the internal waves around 1 m correlate with the ice cover fluctuations of the same period with an approximate amplitude of a few millimeters. These results are consistent with the theory.

Surface wave diffraction at a crack in sheet ice

The time-periodic motions of a liquid layer of finite depth beneath an ice sheet with a straight infinite crack having a periodic dependence on the horizontal coordinate in the direction of the crack are considered. The ice sheet is simulated by a thin elastic plate. It is assumed that the thickness of the plate changes abruptly across the crack. The problems of plane-wave diffraction at a crack, plane-wave diffraction atN cracks in a uniform ice sheet, and plane-wave reflection from a rigid wall are solved. The effect of the pre-existing state of stress of the ice sheet on the properties of the reflected waves is investigated. The condition of nontransmission of fix-frequency waves beneath the edge of the ice is obtained.

Digital Image Processing for Sea Ice Observations in Support to Arctic DP Operations

Various types of remotely sensed data and imaging technology will aid the development of sea ice observation to support estimation of ice forces that are critical to Dynamic Positioning (DP) operations in Arctic waters. The use of cameras as sensors on mobile sensor platforms such as unmanned aerial vehicles in Arctic DP operations will be explored for measurements of ice statistics and ice properties. Several image processing algorithms are adopted to analyze ice concentration, ice floe boundaries, and ice types. The resulting image processing methods for ice observation, including a discussion of possibilities, limitations, and further improvements, are presented in this paper.Copyright

Ice Effect on Coast and Seabed in Baydaratskaya Bay, Kara Sea

For the engineering design of underwater pipelines and communication cables in freezing seas, reliable estimates of the frequency and penetration depth of ice-keel scour on the seabed and shoreface are required. Underestimation of ice gouging intensity on the seabed can lead to the infrastructure damage, while overestimation leading to excessive burial depth raises the cost of construction. Here we present results from recent studies of ice gouge morphology in Baydaratskaya Bay, Kara Sea. The direct impact of ice gouging by floes on the seabed and shores is described, generalized and systematized: the depth of the gouges varies from the first centimeters up to 2 m; the most intensive ice gouging is observed near the fast ice rim, due to the maximum impact executed by ice ridges frozen into large floe. We propose a zonation of Baydaratskaya Bay based on the types of ice formation and the intensity of ice impacts on the coasts and sea floor.

Measurements of sea-ice flexural stiffness by pressure characteristics of flexural-gravity waves

Abstract A method to estimate the flexural stiffness and effective elastic modulus of floating ice is described and analysed. The method is based on the analysis of water pressure records at two or three locations below the bottom of floating ice when flexural-gravity waves propagate through the ice. The relative errors in the calculations of the ice flexural stiffness and the water depth are analysed. The method is tested using data from field measurements in Tempelfjorden, Svalbard, where flexural-gravity waves were excited by an icefall at the front of the outflow glacier Tunabreen in February 2011.

Resonance interactions of waves in an ice channel

Abstract The properties of low-amplitude surface waves propagating in an ice channel are investigated in the shallow-water approximation. The ice cover is modelled either by a rigid cap or by a thin elastic plate floating on a liquid surface. It is shown that an ice channel is a waveguide for surface waves. The dispersive properties of the natural oscillations of the liquid in the channel are investigated. The resonance velocities of the motion of the load on the channel surface, at which the amplitude of the forced oscillations of the liquid increases without limit in time, are determined. The decay instability of the natural oscillations of high harmonics with respect to waves of the first mode is demonstrated. The process is described by the standard equations for non-linear three-wave interaction. The investigations lead to the conclusion that critical modes of motion of a boat are realizable in an ice channel.

Swell wave propagation in an inhomogeneous ice sheet

The propagation of surface waves beneath a periodically inhomogeneous ice sheet is considered. Areas of broken ice and hummock ridges are considered as irregularities. It is shown that waves with frequencies corresponding to wind and swell waves are strongly scattered by the irregularities and are damped exponentially as they propagate beneath the ice.