The regularity and variability of accumulation, ablation, and mass balance distribution on the Djankuat Glacier were investigated to assess the spatio-temporal stability of its external mass turnover fields. A 2019/20-2023/24 time span, characterized by varying degrees of abnormality in the annual budget parameters, was selected as a case pentad for testing. Interannual differences in snow accumulation and melting patterns affect the spatial structure of the fields - obvious shifts of maxima and minima areas are noticed, inter alia. Nevertheless, persistent structural similarities across years indicate a certain degree of temporal and spatial stability. The present analysis employs the field similarity hypothesis originally developed by V.V. Popovnin (1989), which evaluates the variability of the functional relationship between gridded balance parameters and those averaged either over corresponding alti-morphological zones or over the entire glacier. For each grid node, variation coefficients of normalized values are calculated, followed by correlation analysis between the normalized node values and the corresponding zonal and glacier-wide averages. Concerned are both year-to-year correlations and the stability of annual fields relative to the long-term average pattern. Eventually the plots with the highest and lowest stability indices are identified within the glacier area. The alti-morphological zonation is found to align more consistently with the similarity hypothesis than glacier-wide averages. Among the three studied mass-balance parameters, the ablation field demonstrates the greatest stability, whereas the accumulation field exhibits the highest variability. Correlations between annual and multi-year fields exceed those between two arbitrary years. Obtained results can be applied for indirect mass-balance plotting and calculations as well as for predicting accumulation, ablation and overall mass balance patterns.
The article presents results of comparison of the ERA5-Land reanalysis data with results of direct (in situ) measurements of snow depth and the solid precipitation in the permafrost zone in the Magadan Region (Northeast Russia). The analysis was based on daily observations of 21 weather stations (9-850 m a.s.l., 2010-2024) and the authors' data from 12 stationary snow measuring stakes installed at thermometric boreholes of the regional permafrost monitoring network (175-1182 m a.s.l., 2022-2024). The snow depth on the stakes was recorded at a given time interval using camera traps. The ERA5-Land grid nodes closest to the observation sites with a spatial resolution of 0.1 degrees x 0.1 degrees (similar to 9 km) were used for the comparison with regard for differences in elevation between grid cells and observation sites. The results indicate that the ERA5-Land reanalysis systematically overestimates snow depth (on the average by 27 cm or 168%) and solid precipitation (on average by 6 mm or 113% for the period October-April) compared to in situ measurements. The average correlation coefficient between reanalysis data and observations is 0.73 for snow depth and 0.84 for solid precipitation. Divergence increases in mountainous areas and for stations located on the coast of the Sea of Okhotsk. The dependence of the overestimation of snow depth on the elevation of the observation point was revealed. Thus, the overestimation of snow depth reproduced from the reanalysis data increases up to an absolute elevation of about 500 m, but on levels higher 500 m, this dependence changes to the opposite. ERA5-Land shows earlier snow cover formation and later melting in comparison with observations. In addition to the overestimation of solid precipitation, further sources of uncertainties are the low spatial resolution of the ERA5-Land data and the lack of consideration of sublimation and wind-driven snow transport in the model. The findings contribute to a better understanding of the capabilities and limitations of using the ERA5-Land data in the mountainous permafrost regions.
The results of a study of the long-term climatic changes in the "surface air-soil" system to a depth of 3.2 m in the western section of the Baikal-Amur Mainline (BAM) railway are discussed. The monthly average minimum and maximum ground temperatures and characteristics of seasonal freezing and thawing are considered. There are clear regional differences in climatic conditions for the two groups of weather stations. The first group (Lena-Angara plateau and Pre- Baikal depression) is characterized by moderate winter cooling and summer warming in soils with positive mean annual temperature. The type of permafrost thermal regime is long-term seasonal freezing. The second group (Stanovoy Upland basins) is characterized by both moderate (isolated cases) and strong winter cooling in soils. Deep (more than 3.2 & mcy;) seasonal freezing prevails, which in some landscapes merges with permafrost. In summer, the ground warming is moderate and weak. Very weak warming is characterized by thawing only to a certain depth. In most basins, the mean annual temperature is negative throughout the soil profile. The types of permafrost thermal regime in the basins are long-term and deeply seasonally frozen type. Current changes in the climate indicators of the surface air and soil have been identified. Their good consistency has been noted. Positive linear trends in precipitation, air and soil temperatures have been recorded. The BAM region shows significant warming, especially in winter.
During the summer expedition 2025, glacio-climatic observations were carried out on the Levyi Aktru glacier, which marked the beginning of permanent monitoring. Assessments of the glaciological parameters of the Levyi Aktru and Vodopadny glaciers were also carried out using geodetic methods. Interesting features of the altitude distribution of snow accumulation were revealed, and the contribution of summer snowfalls to the variation of the glacier radiation regime during ablation period was noted. Spectral analysis of data series revealed a significant role of mountain-valley circulation in the formation of the thermal regime over the glacier surface, as well as the influence of synoptic variability on the cloudiness regime and the course of relative humidity over the glacier. The obtained data are necessary to identify the mechanisms of Altai deglaciation, assess the glacial component of runoff, and verify models of glacial systems. In particular, calculations of the variability of the main glaciological parameters using the Oerlemans minimal model using measured mass balance characteristics (1977-2012) showed that the Levyi Aktru glacier can be used as a model object.
The paper presents the results of remote studies of cryospheric formations in the microwave range using unmanned aerial vehicles (UAVs). For these purposes, a radiometric receiver with a frequency of 34 GHz with a bandwidth of 2.3 GHz with a fluctuation sensitivity of 0.05 K at a time constant of 1 s was installed on board the UAV. The directional pattern of the corrugated antenna was about 10 degrees. It is shown that this method of monitoring in the millimeter range of media containing ice inclusions is an urgent task, especially in hard-to-reach places. There are a number of difficulties in interpreting the obtained brightness temperature of the radiating medium, which characterizes the power of thermal radiation. The first difficulty lies in the fact that the obtained value of this temperature depends on the angle of observation, therefore, at the time of radiometric studies of cryospheric formations, it is necessary to measure the position of the UAV in space (pitch and roll angles). In addition, it is necessary to take into account the terrain, namely the angles of its inclination relative to the horizon. The second difficulty in interpreting the data obtained from microwave measurements of thermal radiation power is the peculiarity of the medium under study. For example, for a plane-layered three-layer medium with a relatively thin intermediate layer, interference of the brightness temperature is observed, both on vertical and horizontal polarization. Inclusions in cryospheric formations with sharply different dielectric characteristics from the medium itself, for example, gas bubbles in ice, should also be taken into account. The work will be of interest to researchers involved in monitoring various cryospheric environments, both for practical (ice crossings) and scientific (glaciers) purposes.
