Baikal Ice Cover Research Articles

Spherical-Wave Reflection from a Two-Layer Medium and Bistatic Microwave Sounding of the Lake Baikal Ice Cover

Spherical-Wave Reflection from a Two-Layer Medium and Bistatic Microwave Sounding of the Lake Baikal Ice Cover

Natural ring structures on the Baikal ice cover: Analysis of experimental data and mathematical modeling

Hydrophysical studies and mathematical modeling of ring structures during ice cover on Lake Baikal have shown that their existence at the stage of ice cover degradation is due to anticyclonic currents. Such currents can be generated as a result of local upwelling, which we associate with the rise of methane hydrates from the top layer of bottom sediments and their dissociation. Analysis of satellite images shows that the radii of ice rings range from 1300 to 2400 m, which is close to the baroclinic Rossby radius. The measured ice thicknesses in the area of the rings are in agreement with model calculations. Deep water renewal in Lake Baikal can also be associated with the rise of hydrates.

Baikal Ice Cover as a Representative Block Medium for Research in Lithospheric Geodynamics

The paper summarizes the results of long-term field research in the dynamics of the Baikal ice cover as a multiscale block medium similar to the lithosphere in structure, rheology, and seismotectonic features. The analysis covers data on deformation, seismicity, and contact interaction modes as well as on meteorological factors responsible for dynamic fracture of ice plates and strong ice shocks with earthquake-like vibrations. Similarity between seismic features in ice interface zones and zones of tectonic subduction, collision, and shear is discussed. Reasoning from dynamic analogies and similarities of destruction processes in the ice and lithosphere, the research data can help solving fundamental and applied problems, particularly those of earthquake prediction and assessment of contact interactions between lithospheric plates in fault zones.

Radiophysical Monitoring of the Lake Baikal Ice Cover

Presented are the results of the winter 2014 radiophysical expedition, within the framework of which the Baikal ice cover was investigated by electromagnetic methods. The primary objectives the expedition were to detect irregularities in the ice cover, such as cracks and thawing steamed holes in the ice, and to determine the ice thickness and structure in the area of the thawing holes by the GPR sounding method. We used in the experiments the OKO-2 ground-penetrating radar (GPR) of the decimeter band and the nanosecond radar with the wavelength of 3 cm. The measurements were made carried out from the Khivus hovercraft and from the UAZ automobile. The ice thickness of Lake Baikal was determined by non-contact electromagnetic measurement methods. Radargrams of reflected signals from the ice cover are presented. Radar patterns of reflected signals from artificial irregularities of the ice cover were obtained by the short-pulse radar method. The concept of radiophysical monitoring is suggested, which provides a means of determining the ice cover parameters of a water body with high spatial resolution. We present an integral approach to investigating the conditions of the ice cover in order to integrate different physicochemical methods for diagnosing the objects studied. A further development of the concept of integrated ice cover research, and the creation of the monitoring network involves solving a number of scientific and engineering tasks that include developing physical models and information and measurement systems as well as the rationale for an integrated monitoring network.

Radiophysical monitoring of the Lake Baikal ice cover.

Radiophysical monitoring of the Lake Baikal ice cover.

Study of Lake Baikal Ice Cover from Radar Altimetry and In–Situ Observations

Comparison of ENVISAT and SARAL missions data shows that AltiKa can be successfully used for ice discrimination methodology and extension of ice conditions time series. Due to shorter wavelength and large bandwidth (480 MHz) which leads to a higher sensitivity to different surface conditions, AltiKa shows more clearly the separation between open water and various ice types. We observe significant decrease of backscatter (25–30 dB) in late spring for both ENVISAT and SARAL and discuss it in the context of ice metamorphism. There is a clear need to continue and expand our dedicated field studies of lake Baikal ice cover to better assess influence of ice structure on altimetric signal.

Advance in earthquake prediction by physical simulation on the baikal ice cover

The main challenge in the prediction of tectonic earthquakes and their control is still insufficient awareness of seismotectonic processes in the lithosphere and upper mantle during the preparation of strong earthquakes. This is associated in many respects with not quite appropriate equipment for researchers. Among relevant problems is also a lack of adequate models of preparation of earthquake sources at different stages, and this retards the development of earthquake prediction methods. The paper discusses long-term research on deformation and destruction of the Baikal ice cover in the context of physical mesomechanics. With certain combinations of meteorological factors (wind, temperature, precipitation, undercurrents, etc.) responsible for deformation, major cracks of many kilometers arise in the Baikal ice cover. Their spontaneous growth often involves seismic phenomena as ice quakes whose energy reaches Emax = 104–107 J. The nucleation of major cracks is similar to that of rock bursts of moderate strength or weak earthquakes. It is found that ice quakes and earthquakes are both preceded by foreshocks, seismic calm for tens of minutes, aftershocks and other events against the background of accelerated creep in fractures and increased seismoacoustic activity. Research data make it possible to put forward two genetically interrelated criteria among basic factors for ice quake prediction: variations in deformation modes at convergent boundaries of ice sheets and a specific intensification mode-generation of strong foreshocks in a segment in which ice sheets are prepared for dynamic motion. We substantiate the conclusion that simpler and clearer scenarios of preparation of strong seismic events in the Baikal ice cover allow successful physical simulation of preparation of tectonic earthquakes and rock bursts and advances in their prediction. We also consider and substantiate the feasibility of techniques for more efficient seismic risk reduction.

Model study of the formation of deformation-induced structures of subduction type in block-structured media. Ice cover of Lake Baikal as a model medium

The field investigations carried out recently have shown that an effective model medium for studying geotectonic processes can be the ice cover of Lake Baikal, which is a classical example of hierarchically organized block-structured media. Many significant deformation mechanisms of the block-structured ice cover can be compared to the mechanisms known in geodynamics, such as spreading, subduction, pull-apart and other ones. The present paper contains the results of studying dynamic processes of formation and evolution of one of the mentioned deformation-induced structures in the Baikal ice cover, namely, an underride zone that can be considered as a subduction zone analog. It is shown that these processes can be induced by dynamic relaxation events related either to the formation of new interfaces (fragmentation of blocks) or to the activation of the existing but earlier inactive cracks. A supposition is made that fragmentation accompanied by releasing a large amount of elastic energy can be one of possible mechanisms of forming compression impulse, which is considered to be necessary for initiation of subduction in the lithosphere. The processes of forming underride and subduction zones are compared and their qualitative similarity is revealed. After examining the structure of contact between ice plates in the underride zone the conclusion was made that formation of the deformation-induced structure under consideration allows reducing the compression resistance of the plate boundary by orders of magnitude. This suggests that structures of subduction type make for an effective mechanism of realization of high inelastic deformations in block-structured media without noticeable stress growth.

Large-Scale Climatic Controls on Lake Baikal Ice Cover

Abstract Long-term records of winter ice duration, formation, and breakup dates (1869–1996) and maximum thickness (1950–95) on Lake Baikal are analyzed to determine the nature of temporal trends and the relationship with the large-scale atmospheric circulation. There are highly significant trends of decreasing ice duration (and thickness) over the period, associated with later ice formation and earlier breakup dates. These trends are broadly in line with those of winter air temperatures in the region. Variability in Lake Baikal ice formation date, duration, and thickness is significantly related to winter temperatures over a wide area from the Caspian Sea to the Pacific and from northern India to the Kara Sea off the northern coast of Siberia. Thus, Lake Baikal ice cover is a robust indicator of continental-scale winter climate. Correlation and composite analysis of surface and upper-atmospheric fields reveal that interannual variability in ice cover is associated with a tripolar pattern of upper-level ge...

The use of Satellite Imagery in Investigating the Dynamics of the Ice and Snow Cover Lake Baikal

The generation and sample applications of a set of multispectral remotely sensed products for investigations of Lake Baikal's ice cover variability are described. During the period from mid-January to the end of April, the lake is completely covered with ice, and by analyzing satellite information it is possible to investigate in detail the distribution and dynamics of the main types of snow and ice cover. Different ice cover classes and unfrozen water distributions are estimated from calibrated and navigated NOAA AVHRR 1.1-km imagery of Lake Baikal for January 1994 through May 1999. The processing strategy and characteristics of the products are reviewed. The utility of this type of multiparameter dataset for modelling applications and process studies is discussed. ERS SAR and Resurs images are used for detailed representation of different ice classes distributions.

Lake Baikal ice: analysis of AVHRR imagery and simulation of under-ice phytoplankton bloom

Generation and sample applications of an integrated set of multi-spectral remotely sensed products for investigations of Lake Baikal's ice cover variability are presented. Different ice-snow cover classes and unfrozen water distributions are estimated from calibrated and navigated Advanced Very High Resolution Radiometer (AVHRR) 1.1-km imagery of Lake Baikal for January 1994 through May 1998. The calculated downward irradiance field in the photosynthetic available radiance band has served as input for a bio-optical model of phytoplankton dynamics. It is shown that the relationship between the production of main taxonomic groups of Baikal's phytoplankton is highly sensitive to the variability of ice conditions.