Understanding the evolution history of rock glaciers is the key to reveal the response of periglacial environment to climate change. However， the chronology of rock glaciers is relatively inadequate due to the lack of suitable dating materials and other reasons. Quaternary glaciation and periglacial environment were widely developed in Zheduo Mountain， located on the southeastern margin of the Qinghai-Xizang Plateau， which provided conducive conditions for the formation of rock glaciers. Based on the geomorphological investigation and ¹⁰Be exposure dating， we accurately dated a moraine-type rock glacier in Zheduo Mountain and further discussed its formation age and development characteristics. The results show a formation time of rock glaciers in the Zheduo Mountain at about （11.8±0.3） ka， corresponding to the late period of the Last Deglaciation. Millennium-scale climatic cooling events during the Last Deglaciation led to multiple cold and warm climate changes， leading to repeated glacier advances and retreats. The transport and accumulation of a large number of moraines strongly shaped the geomorphic landscape， promoted the continuous expansion of permafrost scale， and also provided the material basis for rock glaciers. Based on the studies of stone glaciers in the Qinghai-Xizang Plateau and other parts of the Northern Hemisphere， it is found that the formation age and evolution characteristics of the rock glaciers during the Last Deglaciation are similar. During the large-scale retreats of the glacier， sudden cooling events lead to the glacier advance and the expansion of the periglacial area， and when the temperature rises， the deglaciated proglacial area becomes a new periglacial environment， and glacial meltwater and sediment are generated at the same time， which promotes the development of the rock glaciers. The glacial and periglacial geomorphological processes， such as the repeated advance and retreat of glaciers， the expansion of permafrost areas， and the development of rock glaciers， caused by climate change， to a certain extent， indicate that the interaction of glacial and periglacial geomorphological processes in the interglacial cycle is the key to understand the response of the cryosphere to climate change.

Based on a review of existing studies and recent work， this paper collects and organizes research findings on glacier mass balance from 2013 to 2023. It summarizes the current methods and models commonly used in glacier mass balance research and reviews the status of such research in China. The results indicate the following： The commonly used methods for glacier mass balance research can be classified into three categories： traditional glaciological methods， geodetic imaging methods， and satellite gravity monitoring methods. Additionally， glacier balance models， which focus on the relationship between glacier mass balance （the algebraic sum of accumulation and ablation） and meteorological variables， have been developed. These models are based on energy balance equations and can be further divided into three subcategories： semi-empirical glacier balance models—degree-day models， energy-balance models， and coupled glacier flow and mass balance models， such as the Open Global Glacier Model （OGGM）. Under the influence of global warming， glaciers in China exhibit an overall negative mass balance trend with significant regional variations. Specifically： The No.12 Glacier in Laohugou， Qilian Mountains， experienced a severe mass deficit， with a cumulative loss of -71 760 mm w.e. between 1991 and 2020. The Kunlun Mountains initially showed relatively stable mass balance， but a negative trend has emerged in recent years. For example， glaciers in the eastern Malan Mountains lost -300 to -180 mm w.e. from 2000 to 2020. Glaciers in the Tianshan Mountains are significantly affected by temperature changes， showing a pronounced negative mass balance trend. For instance， glaciers in the Manas River basin lost -9 811.19 mm w.e. from 2000 to 2016， while the Urumqi Glacier No.1 lost -17 351.5 mm w.e. from 1956 to 2016. Glaciers in the Tanggula Mountains exhibit changes in mass balance similar to those in the Kunlun Mountains but with a more pronounced negative trend. Glaciers in the Dongkemadi River basin lost -7 550 mm w.e. from 1966 to 2015. In the Himalayas， glaciers show a slight negative mass balance. For example， glaciers in the Yamdrok Lake basin experienced a cumulative loss of -930 mm w.e. from 1987 to 2021. Glaciers in the Altai Mountains also exhibit a negative mass balance， with greater losses observed during 2000—2010 compared to the post-2010 period.

Scientific data has become a strategic resource， and scientific data centers， as crucial entities for the long-term storage and open sharing of scientific data， support the development of science and technology innovation. With an accumulation of scientific data construction spanning over 30 years， the National Cryosphere Desert Data Center （NCDC，http：//www. ncdc.ac.cn） aggregates over 60% of scientific data in the domestic glacial， permafrost， and desert research field. In order to promote the open sharing of scientific data resources in these field， NCDC has researched the construction of the resource systems， mechanisms， and methods for scientific data in cold and arid regions. The overall development objective is to build a scientific data system encompassing ice， snow， permafrost， deserts， and related elements， advancing theoretical methods for scientific data and formulate key technologies for the collection， transmission， storage， management， analysis， sharing， application， and product development， creating an integrated scientific data application resource pool that combines data， models， and computation. Simultaneously， assembling a group of interdisciplinary data teams to drive innovative work and establishing a benign development and sharing service ecosystem for scientific data. Additionally， advancing the disciplines of data engineering， key technologies for data engineering applications， and an international alliance for scientific data， constructing research-oriented， production-oriented， and intelligent scientific data centers with international influence， and providing scientific data and decision support for scientific and technological activities， ecological civilization， engineering construction， disaster prevention and control， and diplomatic negotiations in cold and arid regions.This paper reviews the development process and construction strategies of NCDC， summarizing its research practices in the field of scientific data sharing in cold and arid zones， covering aspects such as the construction of standard specifications， data resource management， system platform construction， and the effectiveness and progress of shared services. Finally， future development prospects are provided for the sustainable development of the National Scientific Data Center.

In order to explore the characteristics of winter temperature changes and extreme cold weather in Heilongjiang Province， cope with extreme climate events， daily temperature data and ERA5 reanalysis data from 84 national meteorological stations in Heilongjiang Province during 1961/1962—2022/2023 were selected， and the spatio-temporal distribution characteristics of multi-year temperature in Heilongjiang Province were analyzed by means of synoptic and statistical methods. the atmospheric circulation during extreme temperature was discussed， and the atmospheric circulation index which had better indication of winter temperature was selected. The results show that the winter mean temperature and extreme minimum temperature in Heilongjiang Province are higher in the south and lower in the north， and both show a warming trend， and the extreme cold weather shows a decreasing trend， but the longest duration and maximum influence range of the extreme cold weather have no obvious decreasing trend. The extreme cold weather mainly occurred in the north of Heilongjiang Province， where the Greater Khingan Mountains accounted for 68.7% of the total extreme cold days， followed by the Lesser Khingan Mountains 27.6%， and other regions only 3.7%. Most of the extreme cold weather occurred in January， accounting for 56.9% of the total number of extreme cold weather in winter， followed by December （24.5%）， and February （18.6%）. The abrupt changes in winter mean temperature and extreme cold station occurred in the 1980s， while the abrupt changes in extreme minimum temperature occurred in the 1990s， which are more consistent with the abrupt changes in the Arctic Oscillation， the East Asian trough intensity， and the Arctic sea ice area in autumn. The winter temperature in Heilongjiang Province is mainly affected by the polar circulation， and the southerly polar vortex may lead to a long duration of extremely cold weather in Heilongjiang Province. The Kuroshio Current SST Index， East Asian Trough Intensity Index and Scandinavian Pattern have good correlation with winter temperature in Heilongjiang Province， which have good indication for predicting future extreme temperature changes.

In seasonally frozen ground region landslides are become a more common geological disaster， which has attracted widespread attention in the world. Whether the physical processes of snow ablation and soil freezing and thawing in seasonally frozen ground region， as opposed to the non-monsoon freezing zone， have an impact on landslides deserves further study. A giant loess landslide group （Galamput landslide group） occurred on May 9， 2002 in the Ili region of China provides an ideal case study. By using field survey， remote sensing image identification， meteorological data analysis and loess characteristic test， we attempt to explore the formation process and failure mode， and further reveal the instability mechanism of Galamput landslide group. The results show that the Garamput loess landslide group is composed of three landslides with a total volume of approximately 17.355 million m³. The formation and development of the landslide group was a multi-stage and multiple sliding failure process. The Galamput landslide was the coupling triggering result of early snowmelt and post rainstorm. The snowmelt infiltration and soil freeze-thaw cycle in spring played an important role in the evolution process of slope deformation. The rapid infiltration of extreme rainstorm was the ultimate triggering factor of the landslide. In addition， special slope structures and stratigraphic combinations provide a material structural basis for the occurrence of loess landslides. Combined with the slope deformation process we established a deformation failure model for loess slopes considering the effects of precipitation infiltration and freeze-thaw cycles， and proposed that the combination of static liquefaction on the slip surface and sliding liquefaction at the foot of the slope is an important mechanism inducing the occurrence of loess landslides. In the future， the risk of large-scale landslides in the Ten-zan’s seasonally frozen ground region is extremely high with climate warming. This study can provide a new perspective on the formation process and failure mechanism of loess landslides， and is of great significance for understanding the early warning and risk assessment of landslide disasters in seasonally frozen ground region.

The Svalbard Archipelago is one of the most climate-sensitive areas in the world. Affected by the Arctic amplification effect， most of glaciers there have been undergoing significant shrinkage. Previous studies indicated that mass loss of glaciers in Svalbard accelerated in the past decades， but the ice mass loss caused by surge-type glaciers in the region remains unclear. Based on the high-precision observations from ICESat-2 laser altimetry， this study utilizes an improved classification method to investigate the elevation changes of the Svalbard’s glacier during the period from March 2019 to June 2022. The results show that， from 2019 to 2022， the elevation change of glaciers in the Svalbard shows a declining trend， with an average elevation change rate of （-0.94±0.23） m·a^-1， corresponding to a volume change rate of （-31.62±7.73） km³·a^-1. Among them， the surging glaciers occupy about 22% of the area， with a volume change rate of -13.23 km³·a^-1， accounting for 42% of the total volume change in the glacial area. Therefore， changes in surging glaciers are one of the main factors leading to the whole ice volume reduction in the region. As the largest surging glacier in the Svalbard， Storisstraumen Glacier has expanded its surge area by about 284 km² in the past 20 years， with a volume change rate of -5.67 km³·a^-1， accounting for 18% of the total ice volume loss in the area. Further analysis suggests that the increase in temperature may play a dominant role in triggering the surging of Storisstraumen glacier. This study not only reveals the elevation change characteristics of glaciers in Svalbard during the span from 2019 to 2022， but also quantifies the contribution from surge-type glaciers to the total ice mass loss in Svalbard， which may provide a reference for deep understanding the varying elevation change of glaciers in the region.

The active layer， which is the primary area for permafrost and atmosphere to exchange heat and water， and its morphological changes have a significant impact on ecosystems， topography and geomorphology， surface and subsurface hydrological processes， carbon cycle， and safety of engineering structures in cold climates. In this paper， the spatial distribution characteristics of active layer thickness in the Three River Source Region （TRSR） and its future changes are studied based on the modified Stefan model， and the factors that may affect the variation of active layer thickness are discussed. The results show that the thickness of active layer has been increasing at a rate of 7.2 cm∙（10a）^-1 from 1981 to 2018， and will continue to increase in the future， most significantly in the central part of the TRSR. From 2006 to 2049， the active layer thickness increases at a rate of 4.3 cm∙（10a）^-1 （RCP6.0） to 6.8 cm∙（10a）^-1 （RCP8.5）； from 2050 to 2099， it increases at a rate of 0.04 cm∙（10a）^-1 （RCP2.6） to 4.8 cm∙（10a）^-1 （RCP8.5）， which is significantly less than the rate of increase in the previous 50 years. The rate of increase in active layer thickness has slowed down. Analysis of the factors influencing the variation of active layer thickness shows that the greatest influence is on mean annual air temperature， while the influence of annual precipitation is not significant， and NDVI has some influence on active layer thickness. This result will have an important impact on the water conservation， climate regulation， and ecological security of the TRSR.

Surface energy balance is an important part of the land-atmosphere interaction， which is of great significance for the study of energy exchange， water cycle， climate change and biodiversity. The Qinghai Lake watershed is an important barrier for the ecological security of the Qinghai-Xizang Plateau， and the swamp wetland is the main ecosystem type in the basin. However， there has been little research on the energy balance of swamp wetlands in the Qinghai Lake watershed. Based on this， this study analyzed the variation characteristics of surface energy balance of alpine swamp wetland in Qinghai Lake watershed by using the observed data obtained from the Wayanshan site in 2019. The results show that the surface radiation flux of the swamp wetland at the Wayanshan site has seasonal variation characteristics， and the downward and upward shortwave radiation values are highest in spring and lowest in winter. The net radiation， upward and downward longwave radiation fluxes are the largest in summer， followed by spring and autumn， and the smallest in winter. The net radiation is mainly consumed by latent heat flux and sensible heat flux， accounting for 60.6% and 35.3% of the annual effective energy， respectively. The effective energy is mainly consumed by latent heat flux in summer and autumn， and by sensible heat flux in winter and spring. Compared with other underlying surfaces of the Qinghai-Xizang Plateau， the surface latent heat flux consumes a larger proportion （>75%） of the effective energy in the swamp wetland in summer and autumn. The annual surface energy closure rate of swamp wetlands was 0.69， and the closure rates during the freezing and non-freezing periods were 0.51 and 0.74， respectively.

Glacial lake outburst floods （GLOFs） are a unique type of natural hazard in the cryosphere that may result in catastrophic fatalities and damages. The Himalayas and Nyainqentanglha are second in the world regarding the frequency and severity of the GLOFs after the Peruvian Andes. Slope movements such as ice avalanches， landslides， and rockfalls have been blamed for most GLOF triggers. Despite the intuitive simplicity of the idea behind catastrophic erosional incision by a large wave， this explanation has many possible difficulties. The moraine-dammed lakes are shallow-long lakes， and the solitary displacement wave is the only type wave may be produced by massflows. The overtopping of the moraine dam may be only the first solitary displacement wave because the amplitude damping of the wave is more than 63% during two reflections if the losses of reflections were not considered. However， the erosion is usually a slow process on the hydrodynamic timescale that characterizes the passage of a displacement wave， it is not sufficient that erosion could occur during the relatively fast traversal of the dam. The erosion caused by a single wave was too small to breach the dam. However， it was far easier for a constant water flow to breach the dam by overflowing than for erosion to breach the dam by wave overtopping. A giant wave must be generated by a giant volume of ice avalanches or landslides entering a lake， and result a large water level increasing. The overflowing high water level was the reason for the breaching of moraine dams. Six moraine lakes， drained or undrained， were investigated in Xizang， China. The particle size of armor layers on the surface and the slope angle of these moraine dams and their spillway were measured. A series of laboratory experiments on armor initiated by overflow in the spillway of the moraine dam were conducted. The four statuses of moraine lake were simulated during the experiments. The moraine dam drained when the armor was removed by overflow. The initial model and the critical water depth of the moraine dam breaching were obtained. The initial armor models were the fluvial transport and bed failure models according to the bed slope range. The initial armor model was the fluvial transport model when the bed slope was less than 19.6°. The bed failure model occurred when the bed slope was over 25.2°. When the bed slope was in the range of 19.6°~25.2°， the initial model was a mixed regime. The depth of overflow on the armor and the gradient differences between the upstream and downstream of the knick point were the key parameters to initiate the armor in the fluvial transport model. The relative degree of exposure at the knick point was less and resulted in the first coarse particle initiated by the fluvial transport model occurring at the knick point. The larger the gradient difference between the upstream and downstream of the knick point， the smaller the relative degree of exposure value was. The ratio of the moraine dam’s critical water depth to the armor diameter was inversely proportional to the gradient differences between the upstream and downstream of the knick point in the fluvial transport model. For the bed failure model， the depth of overflow on the armor， the internal friction angle of saturated armor， the bed slope of armor， and the saturated density of the armor were the key parameters to initiate the armor. For the bed failure model of the armor initiation， the ratio of the moraine dam’s critical water depth to the armor’s diameter was a fixed value. The moraine dam breaching prediction model was validated reasonably well by the field data in Xizang， China， and British Columbia， Canada.

The Arctic Monitoring and Assessment Programme （AMAP） Workgroup released a scientific assessment of “Mercury （Hg） in the Arctic” in 2021， which evaluated the contents and storages of Hg over Arctic environmental media and predicted the potential future changes of Hg contents in Arctic environment based on the observational and modelling studies of Hg in Arctic environmental media from recent years. The report stated that global atmospheric Hg emissions originated mainly outside the Arctic （>98%）， and some of which could be transported over long distances in the atmospheric circulation and deposited in Arctic ecosystems， where them participated in the biogeochemical cycling of Hg in the Arctic. The 2/3 of the Arctic atmospheric Hg was deposited to terrestrial environments and 1/3 to marine environments. Hg in terrestrial environments was mainly stored in soils， glaciers， and snow， and could be transported to the Arctic Ocean by riverine transport and coastal erosion. Hg could also be transported into the Arctic Ocean by ocean currents. Hg stored in the Arctic Ocean could be removed by escaping into the atmosphere， burying on the continental shelf and in deep-sea basins， and outflowing by ocean currents. The Arctic environmental Hg was predominantly in inorganic form and could be partially converted to methylmercury （MeHg） by microbial methylation processes in anaerobic environments. Reductions in primary emissions will have a greater impact on future changes of Hg contents in Arctic environment than climate change. And thus stringent and feasible global anthropogenic Hg reduction policies are needed to reduce the ambient Hg levels in the Arctic over the next 20 years. The report also noted that in the future， better quantification of local Hg releases from the Arctic， enhanced research and modelling of key environmental processes for Hg， studies of microbial communities carrying Hg methylation and demethylation genes， consistent projections of primary emissions and climate change， and global inventories of anthropogenic Hg emissions are needed to accurately assess Hg cycling in the Arctic environment and predict changes in Arctic environmental Hg levels.

Understanding the dynamics of glaciers is of paramount importance in the context of global climate change， as glaciers serve as sensitive indicators of environmental shifts. They are key components of the Earth’s freshwater reserves， influencing sea level， water resources， and the global climate system. The study of glaciers， therefore， extends beyond pure scientific inquiry； it has critical implications for predicting future water availability， assessing potential sea-level rise， and developing strategies for mitigating the impacts of climate change. Within this broader framework， glacier surface crevasses offer a window into the deeper processes at work within glaciers. These features are not merely physical anomalies but are indicative of the glacier’s internal and external dynamics. They provide insights into the stress and strain glaciers undergo as they move and deform， offering clues about the glacier’s velocity， the distribution of stresses within the ice， and the interaction between the glacier and its underlying bedrock. Moreover， crevasses influence the energy balance of a glacier’s surface by altering its albedo and affecting its meltwater dynamics， which in turn affects the glacier’s overall mass balance and movement. Thus， the detailed study of crevasses contributes significantly to our understanding of glacier mechanics and their response to climatic variations.This study focuses on the Yanong Glacier， located in the Kangri Karpo Mountain of the southeastern Qinghai-Xizang Plateau， an area noted for its complex terrain and significant glaciological interest. The deployment of Unmanned Aerial Vehicles （UAVs）， particularly the DJI M300 RTK UAV， has facilitated the acquisition of high-resolution orthophotos with a ground resolution of 0.03 m. This technological advancement enables the detailed mapping of glacier surface features， which is crucial for identifying and analyzing crevasse patterns and their distribution across the glacier’s surface.To address the challenges associated with crevasse detection， the study employs a sophisticated deep learning framework， marking a significant advancement over traditional analytical methods. The introduction of the Convolutional Block Attention Module （CBAM）-UNet model represents a novel approach in the field of remote sensing and glaciology. This model enhances the feature extraction capabilities of the conventional U-Net architecture by incorporating attention mechanisms that focus on relevant features for more accurate crevasse detection.The comparative analysis conducted in this study demonstrates the superiority of the CBAM-UNet model over established deep learning models such as U-Net， DeeplabV3+， PSPNet， and HRNet. Achieving a precision rate of 90.74% in identifying ice crevasses， the CBAM-UNet model proves to be exceptionally effective in the extraction of various crevasse types， including Transverse， Splaying， En Échelon， Marginal Crevasses， and Rifts. These crevasse types， indicative of the glacier’s dynamic behavior and influenced by the underlying topography， provide valuable information on the structural integrity and movement patterns of the glacier.The utilization of high-resolution UAV imagery in conjunction with advanced deep learning models offers a robust method for the detailed and accurate detection of glacier crevasses. This methodological approach not only enhances the precision of crevasse mapping but also facilitates the continuous monitoring of glacier transformations. Such advancements are instrumental in understanding the complex responses of glaciers to climate change， contributing essential knowledge to the fields of glaciology and climate science.Furthermore， this investigation sheds light on the potential applications of UAV technology and deep learning in glaciological research， highlighting the importance of interdisciplinary approaches in addressing environmental challenges. The findings of this study underscore the utility of combining high-resolution remote sensing data with machine learning techniques to improve the accuracy and efficiency of glacier monitoring efforts.In conclusion， the research presented herein exemplifies the significant contributions of technological innovations to the study of glacier dynamics. By enhancing our ability to accurately map and analyze glacier surface crevasses， this study offers valuable insights into glacier behavior， the impact of climate change on glacier systems， and the broader implications for water resources and sea-level rise. It is hoped that the methodologies and findings of this study will serve as a foundation for future research in glaciology， promoting further advancements in the understanding and preservation of these vital natural resources.

In the water cycle， water bodies show different characteristics of stable hydrogen and oxygen isotopes （δ¹⁸O and δ²H） in different processes of evaporation， transport， convection， and condensation due to the influences of isotope fractionation. Therefore， δ¹⁸O and δ²H is widely used in the study of paleoclimate and modern hydrological processes. Previous studies mainly focused on the variations of precipitation stable isotopes in the low-altitude regions in the Lhasa River basin， a critical area for the studies of the progressing and evolution of monsoon and westerly wind systems. In contrast， studies on δ¹⁸O and δ²H data obtained from the alpine regions are largely lacking. In this study， we analyzed 347 event scale precipitation samples collected at three sampling sites in the Kuoqionggangri Glacier region from July 2020 to July 2023. The spatial and temporal variations of precipitation δ¹⁸O， the local meteoric water lines， the relationship between precipitation δ¹⁸O and meteorological factors， and the relationship between precipitation δ¹⁸O and convective activity are investigated to understand the influences of the Indian monsoon and westerly wind on the precipitation δ¹⁸O and δ²H in the Kuoqionggangri Glacier region at the source of the Lhasa River of the southern Qinghai-Xizang Plateau. Besides， the backward trajectory of water vapor was further demonstrated through correlation analysis and cluster analysis， so as to reveal sources of water vapor. The results showed that there was little difference in temperature， relative humidity， and precipitation among the three fixed points located in different altitudes in this study area from July 2020 to July 2023 （the glacier terminus （5 544.5 m a.s.l.）， the basin source （5 374.0 m a.s.l.） and the basin export （4 941.3 m a.s.l.））. In addition， the precipitation δ¹⁸O and local meteoric water lines were similar among these three sampling sites from July 2020 to August 2020. This suggested that the climate conditions remained relatively identical within the Kuoqionggangri glacier region. According to the above results， we put emphasis on data of the precipitation δ¹⁸O collected at the basin export from July 2020 to July 2023. The results revealed a two-stage pattern of changes in daily precipitation δ¹⁸O： a higher value before mid-June followed by a lower value. The monthly precipitation δ¹⁸O shows the highest value in June and the lowest value in September. The slope and intercept of the local meteoric water line during the monsoon period （8.12， 11.78） were obviously smaller than those during the non-monsoon period （8.79， 23.18）， indicating that the water vapor source of the precipitation during the monsoon period possessed a higher relative humidity compared with that during the non-monsoon period. The slope and intercept of the local meteoric water line around the year （8.27， 15.10） were more similar to those in the monsoon period. This phenomenon might be due to the large contribution of precipitation in the monsoon period around the year in this region. Monthly precipitation δ¹⁸O exhibited a significant dependence on temperature in the monsoon period. Specifically， the monthly precipitation δ¹⁸O and temperature are positively correlated. Daily precipitation δ¹⁸O were significantly dependent on precipitation amount around the year. Specifically， the daily precipitation δ¹⁸O and precipitation amount are negatively correlated. The convection activity taking place 1~6 days before the precipitation event would deplete the precipitation δ¹⁸O. This influence on the precipitation δ¹⁸O was mainly concentrated in the monsoon period. Results of the backward trajectory tracking analysis indicated that water vapor transported by the Indian monsoon contributed the most to the precipitation of the region throughout the year， which depleted the precipitation δ¹⁸O. This study preliminarily reveals the spatial and temporal variations of precipitation δ¹⁸O and its main influencing factors in the alpine mountains of the southern Qinghai-Xizang Plateau. Results of the current work can provide basic data for the study of water cycle in the alpine regions.

The warming of the Qinghai-Xizang Plateau has led to glacier retreat， permafrost melting， and an increase of meteorological and derived disasters， capturing widespread attention across society. In recent years， the warming of the Qinghai-Xizang Plateau has intensified further. In 2022， the summer was the warmest since 1961， with the average summer maximum temperature （T_max） and minimum temperature （T_min） in the central and eastern Qinghai-Xizang Plateau being 2.37 ℃ and 2.51 ℃ higher than that during the period of 1961—1990. The attribution technique， combining model evaluation and reconstruction， was employed to detect and analyze the anthropogenic influence on the extreme temperature events of the summer 2022 over the Qinghai-Xizang Plateau， utilizing CMIP6 model simulation data. The results indicated that greenhouse gases emissions from human activities significantly heightened the probability of maximum temperature extreme events during the summer 2022 over the Qinghai-Xizang Plateau. The probability of extreme T_max events occurring with and without the influence of human activities was 3.67% and 0.012%， respectively. The contribution of human activities to extreme T_max events in summer 2022 was estimated to be 1.26 ℃ （90% CI： 0.86~1.68 ℃）. The probability of extreme T_min events occurring with and without human activities is 23.5% and 0， respectively. The contribution of human activities to extreme T_min events in summer 2022 was estimated to be 2.35 ℃ （90% CI： 1.89~2.81 ℃）. The CMIP6 model underestimated the observed temperature changes over the Qinghai-Xizang Plateau. The simulation deviation of the model is calibrated based on the attribution constraint method， and the projected summer maximum and minimum temperature over the Qinghai-Xizang Plateau are expected to continue to increase in the future under the medium emission SSP2-4.5 scenario of shared socioeconomic path. The risk of extreme T_max and T_min events similar to those in 2022 occurring on the Qinghai-Xizang Plateau in the future is increasing.

Ice thickness and glacier topography data are the basis of glacial dynamics simulation. The analysis of ice thickness distribution and terrain features is important to understand the characteristics of glacier flow velocity， stress and its change. In September 2021， a ground penetrating radar system was used to probe the ice thickness of the Ningchan River Glacier No.3 in the Qilian Mountains， then using Ordinary Kriging interpolation method to process ice thickness and glacier surface elevation data， and based on the processed data we analyzed the glacier’s profile and whole characteristics of ice thickness distribution and glacier topography， and also studied glacier’s changes in recent years. The results showed that： the thicker parts of the Ningchan River Glacier No.3 were mainly located in the areas where the bed terrain was relatively flat， and broadly the ice thickness value decreased from the center to the edge， and increased first and then decreased with the rise in altitude； compared with glacier surface， the bed terrain of the Ningchan River Glacier No.3 fluctuated more strongly， and the shape of glacier bed in each transverse section appeared in various forms， such as slope， double trough valley and V-shaped valley； the glacier area， maximum ice thickness， mean ice thickness and ice volume of the Ningchan River Glacier No.3 in 2021 were respectively about 1.08 km²， 60 m， 24.1 m and 0.026 km³， and the glacier area， mean ice thickness and ice volume had respectively reduced about 0.123 km²， 3.3 m and 0.007 km³ from 2009 to 2021， and their mean annual change rate were respectively about -1.03×10^-2 km²·a^-1 （-0.86%）， -0.28 m·a^-1 （-1.00%） and -5.83×10^-4 km³·a^-1 （-1.77%）， compared with the period 1972—2009， the glacier shrunk faster， and its primary cause was the rise of mean summer （June-August） air temperature； the change of ice volume was in the form of thickness thinning all the time from 1972 to 2021.

The Qinghai-Xizang Railway （QXR）， a crucial strategic corridor and vital support for Xizang’s economic development in China， extensively employed bridges instead of embankments to protect permafrost during its construction. A total of 156 kilometers of the railway consists of bridges rather than conventional embankments， with 447 bridges constructed， including 125 kilometers of dry bridges， leading to a higher proportion of embankment-bridge transition sections （EBTSs） compared to ordinary railways. However， with global warming and increasing human engineering activities， numerous engineering distresses have emerged in the EBTS in permafrost regions， such as differential embankment settlement， subsidence of wing walls， and bridge structure deformation. Addressing these issues is crucial for ensuring the safe and sustainable operation of this vital infrastructure. This paper reviews and summarizes the current research on engineering distress of the EBTS along the QXR from four aspects： distress types， causes， existing treatment measures， and analysis of faced problems. Additionally， it integrates the latest observations from the QXR’s experimental project on integrated treatment technologies， proposing future directions and recommendations for engineering distress treatment in EBTSs. Research findings indicate that the non-uniform degradation of permafrost induced by the thermal effects of bridge structures is the primary cause of differential settlements in EBTS， contributing up to approximately 50% of the observed settlement. For the numerous dry bridges along the QXR， foundation settlement constitutes the main source of embankment settlement in EBTSs， accounting for over 80% of the total settlement. Bridge structural deformation primarily results from decreased bearing capacity of permafrost foundations and seasonal frost heaving of backfill. Given the lower elevation of EBTSs， protection-cone slopes are subjected to substantial groundwater thermal erosion and intense frost heave， leading to subsidence and cracking deformations. With ongoing warm and rainfall increases on the Qinghai-Xizang Plateau， EBTSs along the QXR face increased risks of distress occurrence in the future. Traditional reinforcement measures are inadequate to address future challenges. The integrated treatment technology has shown promising results in addressing engineering distresses in EBTSs. This technology employs a multi-faceted approach， utilizing innovations such as horizontal thermosyphons， ventilated slope and targeted thermosyphon arrays to achieve comprehensive cooling and regulation of embankment slopes， cone slopes， and foundations. Field monitoring data indicate that this technology has successfully transformed warm permafrost into cryogenic permafrost within a year， concurrently achieving rapid enhancement in structural stability. This technology holds practical significance for enhancing the engineering quality and promoting sustainable development of the railway.

Snow cover is the main controlling factor of the freeze-thaw cycle of seasonally frozen ground in northern Xinjiang， and seasonally frozen ground affects the infiltration of snowmelt water by changing the freeze-thaw phase of shallow soil. However， the freeze-thaw state of shallow soil in the thawing snowmelt season in this region is not clear， making it difficult to accurately assess the synergistic regulation of snow cover and frozen soil on soil moisture from the mechanism level. Therefore， based on the monitoring data of snow cover and frozen ground at six meteorological stations in the Altai Mountains from 1961 to 2011， this study applied the Gaussian model and the Boltzmann model to analyze the basic characteristics of snow cover and seasonally frozen ground in northern Xinjiang on the basis of dividing high snowfall years， low snowfall years and normal years， and discussed the freeze-thaw state of shallow soil during the melting period in detail. The results show that the average duration of snow cover is 123.2 days and the average maximum depth of snow is 29.7 cm. The average annual freezing period of seasonal frozen soil is 150.9 days， and the average maximum freezing depth is 120.3 cm. In general， the snow cover showed an increasing trend， mainly manifested as an increase in snow depth. On the other hand， the frozen soil shows a degradation trend， which is mainly reflected in the shortening of the freezing period and the decrease in maximum freezing depth. The comparative analysis of the end time of the frozen soil melting and the end time of snow melt in different types of snow cover years shows that the end time of frozen soil melting in 70% snowy years and 60.5% normal years is 8.2 and 5.5 days earlier than the end time of snow melt， respectively. The end time of frozen soil melting in the year with low snowfall is 13.2 days later than the end time of snow melting. Overall， the results indicate that as snowfall increases， the probability of seasonally frozen ground being in a thawed state during the snowmelt period also increases significantly. The snowmelt water can recharge soil moisture， which leads to a longer retention time of snowmelt water in the soil. This snow-frozen soil synergistic mechanism significantly affects the infiltration of snowmelt water and alters the snow hydrology runoff process. This process can facilitate more snowmelt water replenishing the soil and strengthens the exchange between meltwater and groundwater， contributing to the effective utilization of snowmelt water in arid regions.

Ice and snow tourism， as a unique form of tourism， not only has significant economic value but also exerts profound impacts on regional ecological environments and social cultures. Due to its unique geographical and climatic conditions， Northeast China has become an important destination for ice and snow tourism in China. On the one hand， ice and snow tourism has brought significant economic benefits to Northeast China. It has promoted local economic development， increased employment opportunities， and improved infrastructure. This influx of tourism-related activities has stimulated various sectors， creating a ripple effect that boosts the overall economy of the region. The economic gains have allowed for better services， enhanced public facilities， and an improved quality of life for the residents. On the other hand， ice and snow tourism faces several challenges， including ecological and environmental pressures as well as social and cultural impacts. Without effective management， these challenges can lead to environmental degradation， resource depletion， and cultural homogenization. The natural landscapes that attract tourists are at risk of being damaged by overuse， and the local culture may become diluted as it adapts to cater to tourists. Currently， the development of ice and snow tourism in Northeast China is also encountering several difficulties and bottlenecks. One major issue is the regional imbalance in tourism development. While some areas， particularly those along the coast， have advanced rapidly， inland areas lag behind， resulting in uneven distribution of tourism benefits. Another significant challenge is the lack of scale efficiency， which hampers the overall effectiveness of the tourism industry in the region. Many areas struggle with unstable resource development， where inconsistent investment and planning lead to sporadic growth and underutilization of tourism potential. These problems not only constrain the sustainable development of ice and snow tourism but also affect the overall competitiveness of the region’s tourism industry. To address these issues， this paper uses the three-stage super-efficiency SBM model to measure the efficiency of ice and snow tourism development in Northeast China. Combined with the pressure-state-response theory， the panel Tobit model is used to analyze the influencing factors of efficiency. The main conclusions are as follows： （1） Analyzing the temporal characteristics， the development efficiency of ice and snow tourism in Northeast China from 2015 to 2023 shows an overall fluctuating upward trend. However， the main cause of inefficiency is identified as scale efficiency. Despite the upward trend， the fluctuations indicate periods of both progress and setbacks， reflecting the complex dynamics of tourism development in the region. （2） From the perspective of spatial characteristics， the efficiency of ice and snow tourism development in Northeast China from 2015 to 2023 exhibits a spatial distribution pattern of “decreasing from coastal to inland areas”. This spatial gradient highlights significant regional disparities in tourism development. The formation of two major ice and snow tourism circles centered around Shenyang and Harbin underscores the concentration of tourism activities and resources in these areas. The average efficiency values follow a descending order from Liaoning Province， Jilin Province， Heilongjiang Province， to the eastern part of Inner Mongolia Autonomous Region. Most cities have not reached the ideal state， revealing prominent issues of regional imbalance and instability in the development of ice and snow tourism resources. （3） The results of the influencing factors calculation show that the development efficiency of ice and snow tourism in Northeast China is affected by various factors related to urban pressure， state， and response. Specifically， the pressure exerted by increasing tourist numbers and activities， the current state of tourism infrastructure and environmental conditions， and the response measures implemented by local governments and communities all play crucial roles. When developing the ice and snow tourism industry， it is essential to balance social pressures with ecological pressures. Strengthening social response mechanisms is vital to mitigate these pressures. This highlights the necessity of addressing regional disparities and promoting balanced development across different areas.

The changes in Qilian Mountain glaciers are not only a direct reflection of climate change， but also has an important impact on fresh water resources. In recent years， the glaciers in Qilian Mountain have been in a state of retreat and instability， to deeply understand the response of the glaciers in the Qilian Mountain to climate change in the 21st century and the magnitude of the change， clarify the characteristics of the Qilian Mountain glaciers change， the process and the reasons， and further predict the trend and magnitude of glacier change， and analyze the Qilian Mountain glaciers destabilization and imbalance in the climate warming background of the mechanism， we selected the Qiyi Glacier， which is strongly influenced by the westerllies， and the Lenglongling No.2 Glacier， which is strongly influenced by the monsoon as examples by analyzing remote sensing images and numerical simulation， it is found that the two glaciers show obvious retreat at the end of the glacier in 1990 to 2022， with the area reduced by 10.28% and 19.04% respectively， and the retreat rate of Lenglongling No.2 Glacier is obviously larger than that of Qiyi Glacier， which is attributed to the fact that the eastern part of the Qilian Mountain is warmer than the western part， and the eastern part of the glacier has decreased in precipitation. To explore the future changes of the two glaciers， the OGGM model considering glacier flow was driven by CMIP6 model data.The relative errors were within 2.5% by comparing the glacier area of the two glaciers simulated by the model and the visually interpreted area from 2008 to 2022. The simulated values of the mass balance of the Qiyi Glacier were more in line with the observed values， with an average difference of 88 mm w.e. Between the two mass balances， the difference between the two is 88 mm w.e.， which indicates that the OGGM model can simulate the glacier changes better.The simulation results show that under the high-emission scenario （SSP5-8.5）， the area and volume of the Qiyi Glacier will decrease by 77% and 94%， and the area and volume of the Lenglongling No.2 Glacier will decrease by 93% and 99% by 2060， and by the 21st century 80s， the air temperature in the area of the Qiyi Glacier will increase by 4.1 ℃ compared with that of the period of 1990 to 2015， while the increase in precipitation will not be obvious， and the glacier will be completely extinguished by that time. In contrast， temperatures in the eastern section of the Qilian Mountain will rise even faster， and it is predicted that the Lenglongling No.2 Glacier will be completely extinct around 2075. Even under the most optimal carbon emission scenario （SSP1-2.6）， a temperature increase of 1.0 ℃ in the Qilian Mountain by 2050 compared with the 1990 to 2015 prognosis will lead to the retreat of both glaciers into ice buckets by 2080 when the area and volume of Qiyi Glacier will be only 22% and 8% of that of 2020， and the Lenglongling No.2 Glacier will be only 17% and 6%. The rapid ablation of glaciers will cause changes in glacier runoff， and the runoff of the Qiyi Glacier and the Lenglongling No.2 Glacier will peak in 2035 and 2024， respectively， and the runoff of the two glaciers will be reduced by 28.98% and 41.82% by the end of the century under the SSP5-8.5 scenario， respectively. Therefore， regardless of climate scenarios， Qilian Mountain glaciers will retreat significantly in the 21st century， or even disappear， due the temperature， precipitation atmospheric circulation， and other influences， which will also make the eastern Qilian Mountain glaciers than the western glaciers retreat faster. Clarifying the trend and magnitude of glacier changes， and understanding the process mechanism of Qilian Mountain glaciers imbalance and destabilization in the context of climate change will deepen our understanding of the current and future glacier changes in the Qilian Mountain region， so as to cope with the environmental and water resource problems caused by the glacier changes， which require us to plan in advance.

The Qinghai-Xizang Plateau （Tibetan Plateau， TP）， renowned as one of the most distinctive geographical landmarks globally， stands as a critical tipping point within the climate system. As the “Asian Water Tower”， this region is highly sensitive to the effects of climate change and could significantly impact the regional climate patterns. Its influence extends profoundly， affecting the climate of East Asia and even the broader Northern Hemisphere. Therefore， it is imperative to comprehend the historical climate patterns and current dynamics of TP. As a proxy for reconstructing past climates， tree rings have been widely utilized in TP climate reconstruction studies. Dendrochronological works in TP have demonstrated a significant potential for developing long tree-ring chronologies over 1 000 years from living trees， archaeological samples， and in situ timber remnants. These records contain temperature and precipitation variability information at multidecadal scales with perfect annual resolution. While numerous literature reviews have focused on different tree-ring parameters， a comprehensive review of dendroclimatological research on TP is still lacking. Therefore， it is necessary to systematically review the research progress of tree ring climate studies in this region. This study retrieved tree-ring chronology data from 1 436 sampling sites across the TP， outlining the progress of dendroclimatology research since 1990. The analysis revealed that most studies utilized tree-ring width （TRW）， followed by maximum latewood density （MXD）， stable oxygen isotopes （δ¹⁸O）， and stable carbon isotopes （δ¹³C）. TRW studies were widely distributed， encompassing nearly 70 tree species， with the length of the chronologies ranging from 300 to 600 years. MXD studies were concentrated in the Hengduan Mountains， focusing mainly on Picea balfouriana， with shorter chronologies and no millennial records. MXD is predominantly used to reconstruct regional temperatures during the growing or late growing season. Studies of δ¹⁸O are primarily located in the surrounding areas of the Hengduan Mountains， Qilian Mountains， and Himalayas. The studied species is substantial， with the longest δ¹⁸O chronology dating back to 4680 B.C. δ¹⁸O mainly records hydroclimatic signals. Studies of δ¹³C are relatively weak， mainly concentrated near the cities of Linzhi and Chamdo and the surrounding areas of the Qilian Mountains. The species most commonly used for δ¹³C studies are Picea crassifolia and Sabina przewalskii. Most of the δ¹³C chronologies are shorter than 200 years， with the longest chronology reaching 1 171 years. Tree-ring δ¹³C is used to reconstruct changes in temperature and hydroclimatic signals. In the future， the accuracy of climate reconstructions can be improved by extending the length of MXD and isotope chronologies， conducting multi-parameter comprehensive analyses， and refining the detrending methods. Expanding sampling sites， particularly in the western and southern TP， is essential to address these geographic gaps. Future research should also explore the climate responses of shrubs and non-coniferous species to enhance the regional dendroclimatological database. Extending the length of tree-ring density and isotope chronologies—especially in northern and western regions—is critical. Given the current reliance of most studies on a single parameter from a single species for climate reconstruction， multi-species and multi-parameter approaches remain uncommon. Therefore， future research should prioritize integrated analyses， combining diverse dendrochronological indicators with climate models to improve the accuracy and temporal depth of multifactor climate reconstructions. Researchers can gain deeper insights into this region's changing frequency and intensity of extreme climate events by integrating tree-ring records and modern meteorological data and combining tree-ring ecology and physiology studies. This study offers a comprehensive overview of advancements in dendroclimatological research in TP， thus providing readers with a clear understanding of the latest developments and the persistent challenges in these studies. Furthermore， this review also summarizes the shortcomings of existing research and lays a theoretical foundation for future in-depth investigations in this field.

Dust microparticles， as key components of atmospheric aerosols， have significant impacts on climate change and atmospheric environments. Based on continuous observations from November 2022 to January 2024， this study systematically analyzed the deposition characteristics of dust microparticles in snow and ice， glacial meltwater， as well as atmospheric precipitation and meltwater-fed Mingyong river water in the Mingyong Glacier， Meili Snow Mountain， southeastern Qinghai-Xizang Plateau. The results showed that： （1） The number concentration of microparticles in glacier meltwater runoff had pronounced seasonal variations， and the monsoon season was higher than in the non-monsoon season. （2） During the period of intense glacier melting （May—October）， the number concentration of microparticle in the Mingyong river water showed notable diurnal variations， nighttime concentrations were higher than daytime values. This phenomenon was mainly attributed to a decrease in the rate of glacier ablation at night， which slowed down meltwater runoff and thus prolonged the retention time of suspended particles in the river water. Through the continuous observation of meltwater runoff during day-night， it was found that the peak concentration of microparticles appeared around 20：00 CST， which further proved that there was a responsive relationship between the diurnal variation of microparticles in meltwater runoff and the strong ablation process of the glacier. （3） Fine particles （0.57~2 μm in diameter） dominated the number concentration of microparticles in water bodies. The volume-diameter distribution of microparticles in different water bodies generally exhibited a unimodal pattern， with small median particle sizes， indicating that dust microparticles in this glacier region predominantly originated from long-range atmospheric transport and deposition. This study revealed the deposition characteristics of dust microparticles in snow， ice and water bodies in the Meili Snow Mountain glacier area， providing significant insights for analyzing the mechanisms of the rapid ablation of the cryosphere and its response to regional climate change in the context of global warming.

Global climate warming causes permafrost to rapidly heat up and gradually degrade into seasonally frozen soil. There are significant differences between permafrost and seasonally frozen soil in terms of soil stability， water transport， and land-atmosphere interaction. Distinguishing between permafrost and seasonally frozen soil is essential due to their distinct hydrothermal dynamics， freeze-thaw behaviors， and sensitivities to climatic variables. This study is based on the coupled hydrothermal model （Simultaneous Heat and Water model， SHAW）， taking Dashalong Station （permafrost） and Arou Station （seasonally frozen soil） in the Qilian Mountains in the upper reaches of the Heihe River as the research objects， to simulate soil temperature， moisture and soil freezing and thawing processes. The results show that the SHAW model exhibits great accuracy in simulating hydrothermal processes at both types of frozen soil sites， but its overall performance is better at permafrost sites. Specifically， the average Nash efficiency coefficients of soil temperature and soil moisture at permafrost/seasonally frozen soil sites are 0.95/0.91 and 0.74/0.37. These findings underscore the SHAW model’s heightened efficacy in simulating permafrost environments， particularly evident in its more accurate representation of soil temperature dynamics. The mean biases in the simulation of soil temperature and soil moisture at permafrost and seasonally frozen soil stations were determined to be 0.56/-1.40 ℃， and -0.001/0.03 m³·m⁻³， respectively. Further examination of simulations pertaining to active layer thickness and the duration of ground surface freezing revealed relatively higher errors at permafrost station. Conversely， errors were comparatively minimal at permafrost station， evidenced by an average depth error of the active layer thickness of merely 10.6 cm and an average error rate of 3%， affirming the SHAW model’s high precision in permafrost station simulations. Conversely， seasonally frozen soil station demonstrated superior performance in simulating maximum frost depth， with a mean absolute error of 21.0 cm and an error rate of 12%. The overall error in surface freezing duration simulations at permafrost stations （9%） marginally exceeded that at seasonally frozen soil stations （8%）. In addition， the freezing and thawing processes are significantly different among different frozen soil stations. The average freezing speed （6.75 cm·d^-1） of the permafrost station during the simulation period is greater than that of the seasonally frozen soil station （1.33 cm·d^-1）， while the average melting speed （2.11 cm·d^-1） is smaller than the seasonally frozen soil station （3.15 cm·d^-1）. Since the underlying permafrost layer of Dashalong Station serve as an “underground cold source”， the seasonal fluctuation range of soil temperature in deep layers （below 80 cm） is smaller than that of seasonally frozen soil stations. The research conclusion can provide a reference for the study of the freeze-thaw differences between permafrost and seasonally frozen soil in the upper reaches of the Heihe River.

MODIS V6 no longer provides binary and fractional snow cover products， but only gives the Normalized Difference Snow Index （NDSI） of pixels. Therefore， when snow mapping based on MODIS V6， the selection of NDSI threshold and the corresponding snow mapping accuracy need to be studied. In this paper， based on the daily measured snow depth data of 250 ground meteorological stations from 2013 to 2021， we evaluate the NDSI_Snow_Cover band in 1927 scenes of MOD10A1 and 1936 scenes of MYD10A1 images in three typical snow cover areas in China. The optimal accuracy and corresponding optimal NDSI threshold of station-by- station pixels in snow cover product mapping were calculated respectively， and the factors affecting the accuracy were analyzed. The evaluation results based on station snow depth show that： （1） The mean ± standard deviation of the optimal NDSI thresholds of MOD10A1 and MYD10A1 were 0.16±0.09 and 0.17±0.10， respectively. The mean±standard deviation of the corresponding OA， FS and CK were 0.96±0.05 and 0.94±0.05， 0.84±0.19 and 0.75±0.24， 0.81±0.20 and 0.71±0.24， respectively. The accuracy of MOD10A1 was better than that of MYD10A1. （2） The optimal accuracy of MODIS snow cover products has obvious spatial heterogeneity. The accuracy in the Qinghai-Xizang Plateau is much smaller than that in the Northeast-Inner Mongolia region and the northern Xinjiang region. （3） In the station-based snow mapping accuracy evaluation， the threshold of snow depth will affect the evaluation results. The accuracy of snow mapping was the highest when the snow depth threshold of 2 cm and 4 cm was used to evaluate MOD10A1 and MYD10A1. （4） SCO and SDI have a significant positive correlation with CK of MOD10A1 and MYD10A1， and the correlation coefficients were 0.72 and 0.77， 0.67 and 0.71， respectively. （5） The terrain of the Qinghai-Xizang Plateau is complex， and the snow is mainly light snow. The snow information of the stations cannot represent the pixels well. Therefore， it is better to use synchronous UAV observation or higher resolution remote sensing images to evaluate the accuracy of snow cover products on the Qinghai-Xizang Plateau.

The stability of permafrost subgrades is closely related to the surrounding hydrothermal environment. Under the influence of climate warming and humidification on the Qinghai-Xizang Plateau， the extensive scale and segmented design of permafrost subgrades in expressways lead to significant ponding issues. Based on long-term field investigations， unmanned aerial vehicle image modelling， and ground-penetrating radar surveys of Gonghe-Yushu Expressway （GYE）， combined with ground temperature and moisture monitoring in typical ponding sections， this study analyzed the spatial distribution of permafrost subgrade distress and their relationship with roadside ponding in the 340-km section from Elashan to Qingshuihe of the GYE. Additionally， it revealed how roadside ponding affected the development of large-scale permafrost subgrade distress. The results showed that subgrade distress in the permafrost sections of the GYE were primarily classified into three types： uneven settlement （77.3%）， transition settlement （13.5%）， and cracks （8.6%）. In the 340-km study section， more than 60% of the sections showed signs of subgrade distress， which were mainly distributed in the high plains and intermountain basins from Changshitoushan to Duoqinankelang and from Yeniugou to Qingshuihe. The distress rate reached up to 60% in permafrost regions with high temperatures and high ice content. The distress rate of the entire study section was 8.4%， while the distress rate in the permafrost section was significantly higher， reaching 18.05%. A strong correlation was observed between roadside ponding and the development of subgrade distress. Approximately 31% of the permafrost sections exhibited roadside ponding， which was mainly distributed in flat terrain. About 66.1% of subgrade distress was associated with roadside ponding. The severity of these distress increased with larger ponding area， greater ponding depth， and shorter distance to the subgrade slope foot. In the ponding sections， moisture content and temperature at the subgrade foot were significantly higher than those in the non-ponding sections， and the permafrost table beneath the subgrade was notably lower than that in the non-ponding sections. Roadside ponding served as a long-term heat source， continuously transferring heat to the permafrost layer beneath the subgrade. During the warm season， ponding absorbed external heat and stored it internally， while simultaneously transferring heat to the permafrost layer. In the early-to-mid cold season， the ponding surface froze， forming an ice layer that acted as a barrier to heat exchange with the external environment. However， due to the high salt content of ponding water， the freezing point was lowered， enabling continued heat transfer from the bottom of the ponding to the permafrost layer. This resulted in a shorter cold season for the soil beneath the ponding area， reducing the amount of cold absorbed by the soil. As a result， the ground temperature in the ponding area increased significantly， leading to asymmetric temperature distribution in the permafrost subgrade area. This process， coupled with increased moisture content， ultimately led to partial thawing of the permafrost layer beneath the subgrade， disrupting the subgrade and inducing various types of subgrade distress. The findings of this study provide valuable insights into the relationship between roadside ponding and subgrade distress in permafrost regions. The results provide a scientific basis for formulating preventive measures and maintenance strategies to mitigate ponding-induced distress in permafrost subgrades. Additionally， the study contributes to a deeper understanding of hydrothermal dynamics affecting subgrade stability and offers practical guidance for future construction and maintenance of subgrades in water-rich permafrost areas. Furthermore， the study highlights the critical role of roadside ponding in the management of permafrost subgrades.

Snow cover has great impacts on the hydrothermal and hydrological states of the underlying active layer， talik and permafrost foundation soils， as well as their mechanical properties and frost hazards. In this paper， by taking into account of the thermal interactions between the buried pipeline and the ambient environment under the dual action of multiple ground freeze-thaw cycles and dynamically changing upper boundary conditions， a coupled numerical hydrothermal model of the buried pipeline and the surrounding pipeline foundation soil is established and applied for predicting the distribution and changes of temperature fields of foundation soils of the China-Russia Crude Oil Pipeline I from Mohe to Daqing， Heilongjiang Province， China. The results show that different upper boundary conditions in the same area have great influences on the temperature field of foundation soils， especially when the actual conditions of snow cover are considered in the upper boundary conditions. Snow cover will greatly affect the distribution of temperature field around the pipe foundation soils and the active layer thickness. At the 30th year of pipeline operation， the maximum thaw depth in the foundation soils under the boundary conditions with snow cover and without on the ground surface would be 6.32 m and 5.39 m， respectively. Snow cover has a good thermal insulation effect on the underlying pipe foundation soils in winter， leading to rising ground temperatures and accelerated melting of ground ice around the pipelines and deepening of the permafrost thaw under the pipeline. Under the condition of the pipeline right-of-way with snow cover， the minimum ground temperature at the depth of 0.05 m and 1 m under the mineral soil surface would be about 4.5 ℃ and 2.4 ℃ higher than that without snow cover， and the occurrence date of the annual minimum ground temperature would be about 10 days later than that without snow cover. Therefore， proper mitigative measures should be taken in the pipeline design， construction and operation phases to effectively reduce the joint thermal influences of the pipelined oil-flows and snow cover on the pipeline foundation soils.

This study investigates the significant role of Antarctic sea ice in the global climate system， with a specific focus on the contribution of coastal polynyas， particularly in the Ross Ice Shelf region. Polynyas， areas of open water within the sea ice cover， are known to be critical sites for sea ice production， influenced predominantly by wind-driven processes. The Ross Ice Shelf polynya， a prominent feature in the Southern Ocean， is one of the most important regions for understanding the mechanisms of sea ice production and its implications for global climate dynamics. The primary aim of this research is to accurately determine the extent of the polynya and the volume of sea ice produced within it， under the influence of wind. Traditional methods for estimating sea ice volume often do not account for the contributions of polynyas， leading to an incomplete understanding of their role in sea ice dynamics. This study addresses this gap by using advanced remote sensing techniques to identify the spatial extent of the polynya， measure the frequency of sea ice production events， and calculate the corresponding volume of sea ice produced. By achieving this， the research provides more accurate estimates of sea ice production in the Antarctic and contributes to a better understanding of its role in the global climate system. To achieve these objectives， the study employs a combination of Sentinel-1 Synthetic Aperture Radar （SAR） data and Advanced Microwave Scanning Radiometer 2 （AMSR2） data. The Sentinel-1/SAR data is used to determine the spatial extent of the polynya during wind-driven events. This high-resolution data allows for precise detection of open water areas within the sea ice cover， which are crucial for understanding the dynamics of polynyas. In parallel， the AMSR2 data is used to measure the thickness of the sea ice that forms within the polynya and is subsequently blown away by wind. By integrating these two datasets， the study is able to accurately identify the boundaries of the polynya during wind events and quantify the volume of sea ice produced. The research focuses on the period from 2019 to 2021 in the Ross Sea region， identifying each wind-driven polynya event and the resulting sea ice production. Additionally， the study analyzes the intra-annual and inter-annual variations in the area， thickness， and volume of ice produced by these events from 2017 to 2021. This comprehensive analysis provides insights into the temporal variability of sea ice production in the Ross Sea polynya and its potential impact on the broader climate system. The findings of the study reveal that wind-driven polynya events in the Ross Sea predominantly occur between mid-March and mid-November each year， with the peak of sea ice production happening in July， August， and September. The average ice thickness during these events ranges from 1 to 30 cm， with the annual frequency of events varying between 72 and 114 occurrences. The volume of sea ice produced in these events ranges from 196 to 284 cubic kilometers， showing a trend of initial increase followed by a decline over the five-year study period. This research makes a significant contribution to the field of polar studies by presenting a novel approach to precisely identify and quantify the extent and impact of polynyas on sea ice production in the Antarctic region. The use of advanced satellite data， combined with a detailed analysis of wind-driven processes， provides new scientific evidence that enhances the understanding of the role of Antarctic sea ice in global climate change. The findings underscore the importance of considering polynyas in sea ice dynamics and highlight their potential impact on climate models and predictions of future changes in the Antarctic environment. This study not only advances the understanding of polar processes but also offers valuable insights into the broader context of global climate variability and change.

In order to reveal the influence of the initial stress state on the dynamic characteristics of frozen clay under the condition of principal stress shaft rotation， a circular stress path of pure principal stress rotation was realized by using the frozen hollow cylindrical apparatus（FHCA）， and a series of hollow torsional shear tests in laboratory were carried out on the basis of the circular stress path， and the effects of the initial stress state on the cumulative plastic strain， stress-strain hysteresis loop and dynamic modulus of frozen clay were studied. The results show that the greater the initial stress of the specimen under the condition of pure principal stress rotation， the faster the cumulative plastic strain development rate of the frozen clay hollow cylindrical specimen， and the greater the final cumulative plastic strain generated. In addition， it is found that with the increase of the initial stress under the pure principal stress rotation condition， the inclination of the axial stress-strain and shear stress-strain hysteresis curves of the frozen clay specimen increases， and the axial resilience modulus and shear modulus of the frozen clay specimen also increase， and there is a linear relationship between the axial resilience modulus and shear modulus and the static deviation stress ratio under different cyclic stress ratios. This research results are helpful to improve the design theory of cold region engineering and artificial freezing engineering.

As an important water conservation area of the upper Yellow River， the Zoige Wetland is crucial in maintaining the stability of the plateau ecosystem and regional climate. Under the background of climate warming， the water resources in Zoige Wetland has changed significantly， which has caused a series of ecological and environmental problems， and further threatened the ecological security and economic development of the middle and lower reaches of the Yellow River. At present， the water resource status of Zoige Wetland has been widely concerned. However， many scientific problems about the water resources in this region have not been solved yet. For example， what are the law of climate change and water resources change in Zoige Wetland in recent decades？ What are the impact process and impact mechanism of the climate change on the water resources in this region？ To solve these problems systematically， based on the observation data at meteorological stations and the hydrological stations in Zoige Wetland， and the ERA-Interim monthly mean reanalysis dataset from 1981 to 2015， this paper research on the regional climate response characteristics and their impact on runoff in Zoige Wetland， by adopting the following research methods， including observation analysis and theoretical research. For the first step， this paper analyze the basic climate change characteristics of runoff in Zoige Wetland. On this basis， we explore the impact process of climate change on runoff in Zoige Wetland. The research work can provide theoretical support for water resources protection and coping strategies of climate change in Zoige Wetland. The results show that， the annual and seasonal average runoff in Zoige Wetland showed a downward trend before 2008 and showed an increased trend after 2008， and the monthly average runoff showed a “bimodal” distribution， with the runoff mainly concentrated in the flood season during 1981 to 2015. Precipitation is the main factor to impact the runoff in Zoige Wetland， and summer precipitation having the most significant impact. The precipitation decreased before 2008 and then increased after 2008， while the continuous rise of temperature， the snowmelt water and evaporation also increased significantly in Zoige Wetland. The evaporation in summer and autumn had the most significant impact on runoff. The annual and seasonal average water vapor flows in via the western and northern boundaries and flows out via the eastern boundary in Zoige Wetland. However， the annual / spring / summer / autumn average water vapor flows in via the southern boundary， and the winter average water vapor flows out via the southern boundary. The inflow from the western boundary is more than from the southern boundary. The net water vapor budget is positive for the whole year and spring/summer/autumn， which is the largest in summer. It is indicated that summer is the season with the most active water vapor transport. Therefore， the Zoige Wetland is an obvious water vapor sink for the whole year and in spring， summer， and autumn， while water vapor is exported from Zoige Wetland in winter. The annual （summer） precipitation is significantly positively correlated with the water vapor inflow at the southern， western boundary and net water vapor budget of the Zoige Wetland in the same period. Southwest wind water vapor transport is an important water vapor transport that causes precipitation anomalies in Zoige Wetland. When the anticyclonic circulation on the southern side of the plateau are strengthened （weakened）， while the anticyclonic circulation in South China and the Western Pacific region are strengthened （weakened）， the southwesterly water vapor from the South China Sea， Western Pacific， and Bay of Bengal transport along the south edge of the Qinghai-Xizang Plateau are strengthened （weakened）， the anomalous southwesterly （easterly） airflow and water vapor convergence （divergence） persist in Zoige Wetland， resulting in more （less） precipitation in summer， and eventually leading to more （less） runoff in Zoige Wetland. We hope this paper can provide a theoretical basis and scientific support for water security and water resources management in the Yellow River basin. Furthermore， the future climate change of Zoige Wetland will be predicted based on the CMIP6 global climate model， and the variation characteristics of water resources in this region under the background of future climate change will be studied. Finally， we try to explore the coping strategies and technical measures of water resources in Zoige Wetland to adapt to climate change.

The warming and humidifying climate on the Qinghai-Xizang Plateau of China is causing permafrost degradation at a faster rate， which is affecting the stability of infrastructure such as highways and railways on it. To resolve this problem， thermosyphons have been widely applied to protect the degrading permafrost in Northeast China and the Qinghai-Xizang Plateau. The thermosyphon has the characteristic of active unidirectional cooling. Existing researches often use numerical simulation or borehole temperature measurement methods to analyze its cooling effect on permafrost foundations. With the development of geophysical exploration technology， ground penetrating radar （GPR） technology provides a new research method for frozen soil engineering， which can obtain continuous data without causing damage to structures. The section of the Qinghai-Xizang Highway from Tuotuo River to Tanggula Mountain Pass was selected as the research area， and GPR technology is used to study the cooling effect of thermosyphons. Based on the investigation of road problems， three typical road sections were selected， where double-sided and single-row vertical thermosyphons， single-sided and single row oblique thermosyphons， and adjacent non-thermosyphons were placed， respectivley. GPR technology was used to detect and analyze structural damage and underlying permafrost distribution. Meanwhile， combined with on-site investigations， the impact of different thermosyphon placement methods on the cooling effect of frozen soil embankment was evaluated. The results indicate that the cooling effect is as follows： double-sided and single row vertical thermosyphons have better cooling effect， followed by single-sided and single row oblique thermosyphons and non-thermosyphon. The distribution of the permafrost layer beneath the double-sided and single-row vertical thermosyphon embankment had good continuity， with an increase of 0.47 m in the upper limit of permafrost compared to the natural surface near the road， and the road structure was entire. The permafrost layer under the single-side and single-row inclined thermosyphon embankment had general continuity， and its permafrost table was close to that of the natural surface. There were areas where structures loosened and cracks happened in the embankment structure. The continuity of the permafrost layer under the non-thermosyphon embankment was lower， and the degradation of permafrost was significant， its permafrost table has degraded by 0.80 m compared to the natural surface. The embankment structure showed large areas of looseness and cracks， and there was water accumulation in some areas. Meanwhile， permafrost degradation can trigger road engineering damages. Comparison showed that the single-sided and single-row oblique thermosyphon embankment and the adjacent non-thermosyphon embankment with permafrost degradation showed loose embankment structures and developed some cracks， and were prone to uneven settlement， cracks， potholes， and other problems. GPR testing can effectively present the distribution of permafrost beneath roads and the characteristics of embankment structural damage. Furthermore， it can used to analyze the mechanism of road surface problems and to provide scientific basis for highway maintenance. Analysis shows thermosyphons can effectively slow down the degradation rate of permafrost， but different placement methods have a certain impact on the cooling effect， the single-sided layout of thermosyphon for high embankments does not cool the warming permafrost. Therefore， it is necessary to scientifically and reasonably carry out the correct design， standardized construction， and effective operation and maintenance of thermosyphon embankments based on the thermal state and structural characteristics of the roads. This can raise the permafrost table under the embankment and reduce or slow down engineering problems caused by permafrost degradation. This study has important practical significance for promoting thermosyphon to be widely used and for improving the serviceability of highways in permafrost regions.

Lake ice phenology is the seasonal change of lake freezing， melting and other phenomena， which plays an important role in indicating regional climate change. This article is based on Google Earth Engine （GEE）， using 250 m spatial resolution MODIS surface reflectance products MOD09GQ and MYD09GQ， and Landsat series remote sensing data to analyze the lake conditions of 10 large lakes （area greater than 200 km²） on the Mongolian Plateau from 2000 to 2021. Ice phenology changes were studied， and their correlation with changes in temperature， precipitation， and Mongolian high pressure was analyzed using meteorological data. The results show that： （1） All lakes begin to freeze from November to mid-to-early December， and are completely frozen from mid-November to late December， entering the lake freeze period； they begin to melt in late April of the following year， and all lakes are completely frozen by the end of May. After thawing， the average lake freeze period for the 10 lakes is 151 days. （2） The overall phenology of lake ice in the study area shows the trend of delayed freezing date， advanced melting date， complete lake freezing period， and shortened lake ice existence period. The specific performance is that the average change rate between the day of initial freezing and the day of complete freezing is 1.88 d·（10a）^-1 and 1.91 d·（10a）^-1， respectively； the average rate of change on the day of initial thawing and complete thawing is -3.45 d·（10a）^-1 and -3.41 d·（10a）^-1； the average change rates of the lake ice existence period and complete freezing period are -5.32 d·（10a）^-1 and -5.37 d·（10a）^-1，respectively. （3） Climate change will affect the phenological changes of lake ice in the study area， and temperature is the key factor affecting the phenological changes of lake ice. Rising temperatures lead to a delay in the freeze-up start date （FUS） of lake ice， an advance in the break-up start date （BUS）， and a shortening of the complete freezing duration （CFD）. At the same time， the phenological properties of lake ice in some lakes will be affected by the Mongolian high pressure in winter， which will bring the cold air will cause the lake ice break-up duration （BUD）， lake ice cover duration （ICD）， and complete freezing duration （CFD） to increase.

This study investigates the mechanical properties of silty soil in seasonally frozen regions， stabilized using lignin fibers in conjunction with microbially induced carbonate precipitation （MICP）. A series of experiments were conducted， including assessments of calcium carbonate production influenced by lignin fibers， unconfined compressive strength tests， direct shear tests， and scanning electron microscopy （SEM） analysis of lignin fiber-MICP stabilized samples subjected to freeze-thaw cycles. The results indicate a linear increase in calcium carbonate content with increasing fiber content， with the calcium carbonate content in the SF2M sample exhibiting a 426.6% increase compared to the SF0M sample. With an increase in freeze-thaw cycles， both the unconfined compressive strength and shear strength of all samples diminished， eventually stabilizing. Among the samples， the SF1.5M， containing 1.5% lignin fiber， demonstrated the highest resistance to freeze-thaw degradation. After 10 freeze-thaw cycles， its unconfined compressive strength decreased by only 45.9%， whereas the SF0M and SF0 samples showed reductions of 63.4% and 80.0%， respectively. Furthermore， after 10 freeze-thaw cycles under a normal stress of 400 kPa， the shear strength of the SF1.5M sample increased by 76.4% and 184% compared to the SF0M and SF0 samples， respectively. Cohesion in the SF1.5M sample also improved significantly， with increases of 46.5% and 126.0% over the SF0M and SF0 samples. At a fiber content of 1.5%， a denser cemented structure formed between soil particles， calcium carbonate crystals， and fibers， enhancing soil stabilization. However， when the fiber content reached 2.0%， calcium carbonate crystals intertwined with the fibers， forming aggregates that impeded the effective cementation between soil particles， thereby diminishing the stabilization effect. In conclusion， this research offers important data and theoretical guidance for soil reinforcement in cold regions， particularly under the influence of freeze-thaw cycles. The findings contribute to the understanding of soil stabilization mechanisms and provide practical insights for improving the mechanical properties of silty soils in seasonally frozen environments.

The chain reaction of glacial lake outburst floods in the alpine and high altitude mountains area poses a significant threat due to its extensive impact range， large flood scale， and high flow velocity. Traditional prevention and control measures downstream of the disaster chain are often difficult to implement and economically unfeasible. Moreover， the primary triggering factors， such as ice collapses， are usually located at altitudes above 5，000 m， making access and engineering interventions extremely challenging. To address these issues， this study proposes a novel prevention and control approach focusing on the overflow outlet of the moraine dam， based on field investigations and statistical analysis. A new integrated protective system， combining rigid and flexible reinforcement layers， is developed to enhance the stability of the moraine dam’s armor layer at the overflow section. The system consists of scaffold steel pipes， high-strength metal flexible nets， and anchor rods， forming a “rigid-flexible integrated plate-like” protective structure. Laboratory physical model experiments were conducted to verify its effectiveness under simulated flood conditions. The results indicate that as protection measures are strengthened， the initiation flow velocity of the armor layer increases significantly. Compared to the unprotected state， a single-row rigid connection provides a minimal increase in stability， whereas a double-row rigid connection increases the initiation flow velocity by approximately 2%， a triple-row rigid connection by about 5%， and the combined rigid-flexible system by approximately 8%. The effectiveness of the protection system improves with an increase in the protected area， demonstrating its potential for mitigating moraine dam breaches. This research provides a feasible and technically viable solution for preventing moraine dam failures in high-altitude， cold environments. The proposed system offers advantages in terms of adaptability， cost-effectiveness， and ease of implementation in remote mountainous regions. It has the potential to serve as an effective first line of defense against glacial lake outburst floods and contribute to disaster risk reduction in alpine and high-altitude areas.

With the rapid advancement of China’s economy and accelerating urbanization， the proportion of subways in urban transportation networks is steadily increasing. The artificial ground freezing method is an essential construction technique for tunneling through soft， water-saturated soil layers. The frost heave-induced deformation of the ground surface resulting from this method may adversely affect adjacent existing engineering structures. In extreme scenarios， it could lead to significant economic losses and pose a threat to human safety. Therefore， considering the crucial factor of ground surface deformation caused by soil frost heave becomes imperative during the horizontal freezing construction of shallow buried tunnels. The investigation into the redistribution of the soil layer displacement field induced by artificial ground freezing and its resulting ground surface uplift deformation has garnered significant attention among scholars； however， certain limitations are present. To overcome the limitation of previous studies that overlook the spatial variability in frost heave ratio resulting from a non-uniform temperature field， the article proposes an innovative methodology for quantifying ground surface deformation induced by frost heave during underground tunnel construction. The proposed method integrates the principles of superposition and the theory of random media within the framework of thermo-elasticity mechanics， utilizing the concept of an equivalent thermal expansion coefficient. The presented approach was employed to calculate ground surface deformation induced by soil frost heave due to single-loop distribution freezing pipes， based on an engineering case study. The rationality and applicability of the presented method were demonstrated through a comparison with observed values. The calculation results obtained from this method demonstrate a markedly higher degree of agreement with the observed values compared to those achieved by conventional approaches and finite element method （FEM）. Conventional approaches typically assume a constant frost heave ratio and estimate stress and deformations using the principles of thick-walled cylinders. The FEM is based on the principles of “cold expansion and hot contraction” and employs thermal-mechanical coupling to simulate frost heave phenomena induced by artificial ground freezing. In contrast to the presented approach， the conventional model fails to consider the reduction in soil frost heave ratio near the outer side of a frozen soil wall due to higher temperatures， leading to an overestimation of computational results. Compared to FEM， the approach proposed in this study is more straightforward and practical， while also providing deeper insights into underlying mechanical principles. In addition， the investigation focused on the distribution of ground surface frost heave deformation induced by the artificial ground freezing， taking into account the influences of refrigerant medium temperature， burial depth of the tunnel center， and freezing front extension coefficient ε. The results indicate that as the refrigerant medium temperature decreases， there is a notable overall increase in ground surface deformation， with particularly pronounced effects observed above the center of the tunnel. The appropriate selection of coolant medium temperature is crucial for ensuring the safety and stability of adjacent existing structures. The central buried depth of the tunnel， to some extent， reflects the average embedment depth of freezing pipes and serves as a critical factor influencing ground surface frost heave deformation. With an increase in the burial depth of the tunnel， both the maximum deformation caused by ground frost heave and its influence range gradually diminish. The distribution of ground surface frost heave deformation is closely correlated with the depth of the tunnel center， which in turn governs the magnitude and extent of ground surface deformation. The maximum ground surface frost heave deformation and the affected area exhibit a slight increase as ε increases， although this increment is not significant. This study can provide reference for the application of artificial ground freezing technology in high-risk underground engineering projects.