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We experimentally and numerically demonstrate the inability for picosecond telecom pulses to form a single multimode soliton in a graded-index fiber. This property is useful in space-division multiplexed systems, to transmit independent soliton channels which do not merge into a single multimode soliton.

Despite the low mean annual air temperature and low precipitation, subaerial suprapermafrost aquifer taliks are formed in some cases in the continuous permafrost zone of Central Yakutia. The paper presents an analysis of the seasonal and interannual dynamics of ground temperature in contrasting geocryological conditions - in areas of permafrost spread from the surface and in suprapermafrost subaerial taliks - of the key area of Levaya Shestakovka 20 km southwest of Yakutsk. The permafrost table in this area a occurs at depths from 0.5 to 20 m. The highest ground temperatures are typical of the area of aquiferous suprapermafrost taliks confined to gentle slopes composed of sandy sediments and covered with pine woodland. The thickness of the seasonally frozen layer reaches 3 m, and the depth of zero annual amplitudes varies from 6 to 12 m. Thawed deposits are preserved due to the continuous filtration of groundwater in them. The lowest ground temperatures are characteristic of the mire and the river floodplain. The depth of seasonal thawing varies from 0.5 to 1.0 m, and the depth of zero annual amplitudes exceeds 15 m. In recent years, slow freezing of the taliks from below has been noted due to mild cooling of the strata underlying the thawed aquifers. Beyond the area of taliks, weak multidirectional changes in ground temperature have been recorded.

Based on observations on 12 largest rivers of East Siberia (Lena, Vilyuy, Kolyma, Aldan, Olenek, Vitim, Indigirka, Amga, Olekma, Anabar, Yana, and Chara) during summer low-water runoff in 2007-2011, the main features of the chemical composition and physical properties of river water have been determined. It is found that favorable oxygen regime, higher chemical oxygen demand and color of water, higher concentration of total iron and ammonium ions, and moderate salinity are characteristic of the investigated rivers. The territory of East Siberia is characterized by an ubiquitous distribution of permafrost. The thickness of seasonally thawed layer within river catchments is extremely variable in the studied region. Using canonical-correlation analysis, it was found that concentrations of specific components of ionic constituents (water hardness, calcium, magnesium, bicarbonates, sulfate ions, and salinity) depend on the active layer thickness (ALT). Herewith, the deeper the active layer in a catchment, the higher the concentration of mentioned components of ionic constituents. This pattern is explained by the fact that permafrost serves as a confining barrier that prevents infiltration of surface water through deep mineral horizons thus restricting water saturation with mineral ions. The increase in ALT noted in recent decades in the permafrost zone of the northern hemisphere may continue in the current century. Therefore, knowledge of how the concentration of soluble biogeochemical constituents in the rivers depends on ALT of permafrost in the catchments is valuable for assessment of potential changes in the chemical composition of river water in the permafrost zone in the future.

To date, the issue of using ice-based composite materials for engineering constructions under harsh weather conditions remains poorly understood. Application of ice as construction material is favored by its ease of use and low manufacturing cost. In turn, ice can be reinforced with various additional materials that change its physical and mechanical properties as part of an ice-based composite material. The results of an experimental study of the behavior of reinforced ice beams under pure bending are discussed. As a reinforcement, longitudinal rods with different physical and mechanical characteristics made of fiberglass and polypropylene were used. The results of the study were compared with previous experiments on loading ice beams reinforced with steel armature. It is concluded that the proposed materials can be efficiently used to improve the mechanical characteristics of the ice. There is a positive effect of polypropylene on the deformability of the samples, as well as their bearing capacity. Schematic diagrams of deformation of ice beams reinforced with steel and fiberglass reinforcement and with polypropylene rods are presented. Prospects for the use of fiberglass and polypropylene rods in the ice-based composite materials are discussed.

The article presents the initial assumptions of the predictive model of changes in the temperature regime of the frozen soil massif in the case of surface flooding. Heat exchange of the soil surface with the atmosphere through a shallow (up to 1 m) water cover is described using an effective heat exchange coefficient, which includes the intensity of mixing of the water layer during the summer season. The results of calculation of two parameters of the new thermal condition of the frozen massif (temperature at a depth of zero annual amplitude and the maximum depth of seasonal thawing) appearing as a result of flooding are presented. In addition, the rate of transformation to the new condition is considered. Significant warming of the frozen foundation soil occurs in the case of intense mixing of the water layer during the summer season. If the mixing process does not take place in the water reservoir of a shallow depth, its cooling effect is possible. In deeper reservoirs, the warming effect is possible, but it is weaker than that under mixing conditions. This analysis has been performed for the least studied element of the “roadway embankment - reservoir - frozen soil” technical system in order to control the correctness of the calculation procedure in a more complex case for a two-dimensional process. The results of mathematical modeling of the temperature field in the frozen base of the roadway in contact with shallow water basin are presented. It is demonstrated that the frozen base warms up essentially, if the water layer is intermixed intensively (by wind) in summer time. The initial temperature state may be preserved during the whole period of road exploitation, if the summer mixing of water is blocked by fairly simple technical measures that are proposed in this paper.

The morphology and mineral composition of cryogenic formations of the Malaya Nizhneudinskaya Cave have been studied by electron microscopy and X-ray powder diffraction. This cave is confined to permafrost. The temperature in the cave is near zero all year round, as a result of which ice formations are widely developed in the cave. When solution freezes, and the subsequent partial evaporation of ice occurs, a cryogenic residue composed of gypsum, calcite, and a rare mineral rapidcreekite Ca₂(SO₄)(CO₃)·4H₂O is formed. Rapidcreekite forms radial-radiant aggregates of acicular crystals of up to 200 μm in length. In our opinion, the source of sulfur is represented by the locally developed interlayers of gypsum in the non-karsting rocks overlaying the limestones. This is the second finding of rapidcreekite in the speleo-cryomineralogenesis environment in the world and the first discovery of this mineral in the caves in Russia.

Erosion plays an important role in removing permafrost degradation products. In order to identify the rates and mechanisms of erosion in degrading permafrost, fluvial landforms in small catchments at the foothills of the Kharaulakh Range were typified, and their morphology, formation conditions, and dynamics for 2019-2022 were characterized. The most dynamic landforms associated with melting ice wedges were thermokarst runoff troughs (water tracks), rills, and thermoerosional gullies. Thermoerosional gullies forming in sediments without wedged ice grow upon very high floods; in the rest of the time, their sides slowly slide down under the action of snowfields. Sediments from gullies and rills are deposited in the upper reaches of small rivers. The channels of small rivers are relatively stable, which is also typical of other permafrost regions. Differences in the dynamics of erosional landforms can be explained by an increase in the thermal rather than mechanical impact of water on frozen deposits, which is observed with the rise in air temperature against the background of relatively stable precipitation in the north of Yakutia.

The elaborated method of regional calculation of the hydrological regime of glaciation includes determination of long-term changes in glacial runoff and glacial feeding in river basins. For the Rhone River basin, monitoring data on glaciation parameters over the period of 1971-2016 and long-term data on precipitation and air temperature at weather stations of Switzerland were used for hydrological and glaciological calculations. The results of linear extrapolation of spatiotemporal changes in the altitude-area characteristics of the classified groups of glaciers proved to be sufficient for calculating the hydrological regime of glaciation. An adequate description of seasonal and long-term glacial feeding of rivers should take into account spatiotemporal variations in the ablation of glaciers depending on the five types of active glacier surface and their altitude-area characteristics. Satisfactory absolute and relative estimates of differences between the measured runoff and the amount of precipitation, evaporation, and glacial feeding in the upper Rhone River in 1971-2010 (Porte du Scex gauging station), as well as between the measured and calculated annual precipitation in the Rhone River basin for 1971-2016, were obtained.

The reasons and conditions for the formation and change of moulins are considered on the base of author’s own data and on published data. Moulins can form above the water level in crevasses in the ice column and cannot form below the water level. The cylindrical shape of moulins is associated with the spraying of water jets at a certain depth from glacier surface. Questions related to different mechanisms of moulin formation, their depth, age, water level fluctuations are considered. A possible connection between moulins and the internal drainage system of glaciers is shown. Since there are glaciers in which water does not penetrate to the bed through moulins, the question of the connection between moulins and thrusts in the ice thickness is being considered.

Changes in the Earth’s insolation by latitudes and seasons in certain periods of the Holocene are considered. A comparative analysis of insolation in boundary years of Holocene geochronological periods with modern insolation (2022) is carried out. The change in summer insolation in the hemispheres is analyzed separately. Quantitative estimates in the intensity of insolation’s changes in the Holocene are assessed with respect to the modern insolation. The extremes of summer insolation in the Northern hemisphere are synchronized with the global paleogeographic events of the Holocene: the transition from the cold Pleistocene epoch to the warm Holocene and the Little Ice Age. Characteristics of the Earth’s orbital motion have also been shown to control the Northern hemisphere summer insolation’s change, which is a factor of the noted global paleogeographic events.