The Cryospheric Science has developed rapidly since 21st century under the background of global warming. This paper summarizes the development process and briefly introduces the basic framework of Cryospheric Science on the basis of reviewing the international and Chinese relevant researches on cryosphere. Since the concept of cryosphere was officially proposed in the 1970s， the international community has taken more attention on the impacts of cryosphere in the interactions between other spheres while deepening the understanding of the mechanisms and process of the cryosphere， which can be marked with the launch of the Climate and Cryosphere （WCRP-CliC） plan and the establishment of the International Association of Cryospheric Sciences （IACS）. It indicates that the study of the cryosphere tends to along the mainline of change - impact - adaption， and has illustrated the core characteristics of Cryospheric Science in a certain extent. The study on Chinese cryosphere has been developing rapidly following the mainline of Cryospheric Science in the past 20 years， especially in the past 10 years. It has presented systematic achievements in terms of changes in the cryosphere and the impacts of changes in the cryosphere on ecology， hydrology， climate， surface environment， society and economy， and also get systematic understanding of the connotation and extension of the Cryospheric Science. Based on short introduction on the background of the gestation and development of the Cryospheric Science and a brief summary of the current status of cryospheric research in China， the paper discusses the disciplinary framework of Cryospheric Science from the scientific connotation and extension， research methods， to discipline constitutes. It suggested that Cryospheric Science has become a new discipline involving a wide range from process and mechanisms to impacts and adaptation， which closely related to sustainable development.
Adaptation research of cryosphere is a novel research direction in the field of cryosphere science， and it is a typical representative of the interdisciplinary integration of natural sciences and social sciences in the study of global change. This paper elaborates the content framework of the adaptation research of cryosphere， and analyzes the present situation， dynamics and development trend of the international adaptation research of cryosphere change. The adaptation study of the cryosphere in China is introduced in detail from aspects both of theoretical exploration and practical research. In terms of theoretical and methodological research， China has established a research theory and methodology system for the adaptation of cryosphere since 2007， which is composed of the impacts of cryosphere change， including cryospheric service and cryospheric disaster-risk-resilience-adaptation. In terms of practical study， research on the cryospheric service and the risk assessment of cryospheric disaster are carried out from two lines of profit and harm. Typical case studies on the vulnerability， resilience and adaptation of cryosphere are implemented from the perspective of interaction between cryosphere and anthroposphere. In the future， on the one hand， the existing theoretical system needs to be further improved and deepened， especially the quantitative assessment method of disaster risk， vulnerability and adaptation； on the other hand， we should not only strengthen the case study for different cryospheric problems， but also expand the scale， go deep into macro research， and provide scientific basis and countermeasures for the decision-making of national and local governments.
Continuously affected by climate warming， the hydrological processes are undergoing significant changes in Chinese cryosphere. Based on the summaries of the past changes of cryospheric meltwater， this paper focuses on the analysis of the future change characteristics of the cryospheric meltwater runoff， especially the tipping point of glacier meltwater and possible trend of glacier meltwater corresponding to an air temperature rise threshold of 2.0 ℃ by the middle and end of the 21st century. Furthermore， we study the impacts of cryospheric hydrological changes on water security of river basins， especially in arid inland river basins. The results show that the glacier meltwater runoff will decrease in most catchments of China. The future changes of glacier runoff will show three types： continued decrease， reaching peak in the near future and sustainable increase in catchment scale. The meltwater of single glacier will likely reach tipping point in future. And there are good relationships between the occurrence time of tipping point and the rising temperature rate and glacier size. The glacier runoff will still increase steadily until 2050 in the high glacierized basins consisted of large glaciers. While the glacier runoff has reached the tipping point in small glacierized basins. For other glacier catchments， the glacier runoff will reach peak point or show no significant change until 2020 - 2030. Overall， the glacier meltwater will decrease by 34% - 74% in northwest arid regions corresponding to an air temperature rise threshold of 2.0 ℃ under RCP global emission scenarios by the end of the 21st century. The cryospheric hydrology changes will lead to the decrease of water supply， conservation and regulation capacity， the increase of variation coefficient of annual runoff and drought/flood risk， and the advance of spring flood， which can further affect the water utilization system.
The China-Pakistan Economic Corridor is a key route connecting the north-south silk road. Due to global warming， the situation of glacier changes in this region is complex， some glaciers appear advancing and surging， the risk of glacial lake outbreak is rising， which threatens the construction of the China-Pakistan Economic Corridor and people’s livelihood. Based on remote sensing images from Landsat TM/ETM/OLI from 1990 to 2018， this paper extracts the data of glacial lake outbreak from three Glacial lake Catalog along the China-Pakistan Economic Corridor by means of visual interpretation， and analyzes the overall change trend， spatial heterogeneity and causes of glacial lake outbreak in the corridor over the past 28 years. The results show that there are currently 2 380 glacial lakes in the corridor， with a total area of （131.76±19.08） km2， concentrating in the Karakoram Mountains and the Himalayas； between 1990 and 2018， the overall area of the glacial lake had expanded with a rate of 0.48%·a-1， but the size of the glacial lake varies widely from place to place； in the China-Pakistan Economic Corridor， under the combined effect of temperature and precipitation， the area of glacial lake is expanding now， at the same time， the spatial differences in temperature and precipitation change rates result in the change of glacial lake area with spatial difference； the rapid retreat of the glacier is increasing the risk of glacial lake collapse in the corridor.
The cryosphere is an important component of the climate system， and the glaciers are the crucial part of the cryosphere. The constitutive equations and modeling of glaciers， especially mountain glaciers， have always been the core task of glacial dynamics. This study briefly reviewed the research and development on glacier model which includes the three-dimensional glacier model used the Navier-Stokes equation coupled with the temperature field and some basic concepts of model simplification， such as the hydrostatic pressure approximation， the first order approximation， and the shallow ice approximation. Based on the summary on the primary method of establishing the dynamic numerical model of glaciers this study also introduced a typical example of ice sheet model GLIMMER and its application in research area. Finally， considering the poor representation of simplified numerical model of mountain glaciers， especially in the descriptions of their physical processes and spatiotemporal variations， a dynamical framework of mountain glacial model based on the complete Navier-Stokes equation and the corresponding treatment of boundary condition are proposed in this study. This study could provide basic knowledge and reference for the establishment and development of the glacier and ice shelf models， especially for the mountain glacier models.
This study focuses on the relationship between soil moisture anomalies caused by the freezing and thawing process and summer precipitation in the Northern Hemisphere. The spatiotemporal characteristics of spring soil moisture in seasonal freezing-thawing areas and summer precipitation in the Northern Hemisphere and their relationship are analyzed using the singular value decomposition （SVD） with ERA5 monthly reanalysis data. It is found that there is a good correspondence between the area of large annual variation of soil moisture in spring and that of precipitation in summer in seasonal freezing-thawing area over the Northern Hemisphere. There is an exponential function relationship between spring soil moisture and summer precipitation in seasonal freezing-thawing areas. In northwest of America， West Asia， and most part of East Asia， spring soil moisture and summer precipitation are significantly positively correlated. It indicates that the increase of soil moisture in freezing-thawing areas corresponds well with the increase of the summer precipitation.
Snow cover classification is of importance for knowing snow properties and their temporal and spatial distribution. It is the climate that ultimately determines the physical characters of snow cover through temperature， precipitation and wind. Therefore， snow cover classification can be derived from the important climate variables. In this paper， a snow cover classification in China is put forwards based on binary system of the three climate variables proposed by Sturm et al. using long serise of China meteorological dataset， and the snow cover characteristics’ distribution is statistically analyzed and validated by in-sit measured data from Science & Technology Basic Resources Investigation Program of China （investigation on snow characteristics and their distribution in China）， which laid the foundation for formulating a snow cover classification system with China’s regional characteristics. The results show that spatial resolution of the snow cover classification in this paper has increased significantly as compared with that in the study of Sturm et al. The snow cover types in China can be divided into five types： prairie， taiga， tundra， mountain and ephemeral types. Different types of snow cover in China show snow characteristics different from Sturm-Holmgren-Liston （SHL） classification.
Based on the daily data of snow cover depth from 89 meteorological stations in Xinjiang over the period of 1961-2017， the spatial-temporal change of the maximum snow cover depth and days with snow cover were analyzed by the methods of stastics and diagnose. It was found that： （1） The maximum snow cover depth in winter in the north was more than in the south. The maximum snow cover depth was 60-100 cm in Altay and Ili Valley， and 30-60 cm in north slopes of the Tianshan Mountains， and under 20 cm in Southern Xinjiang. The maximum snow cover depth in Northern Xinjiang mostly occurred after 1996， which was also the period when the climate of Xinjiang changed from warm-dry to warm-wet； （2） The maximum snow cover depth increased significantly in winter in Xinjiang region， Northern Xinjiang and Tianshan Mountains， and slightly in Southern Xinjiang. About 87.6% of the 89 meteorological stations showed an increasing trend， while 20 stations increased significantly， mainly in the Northern Xingjiang； （3） 48%-58% of the total number of days with snow cover was in snow cover depth less than 10 cm， 24%-32% of that was in snow cover depth between 10 and 20 cm， 12%-15% of that was in snow cover depth between 20 and 30 cm， and 5% of that was in snow cover depth greater than 30 cm in Xinjiang region， Northern Xinjiang and Tianshan Mountains； （4） In these regions， the number of days with snow cover showed slightly decreasing trend， the number of days in snow cover depth less than 10 cm decreased， especially in Northern Xinjiang， and the number of days in snow cover depth more than 20 cm increased significantly； （5） In Southern Xinjiang， the snow depth was mainly less than 5 cm and the change trend of the duration of snow cover was not obvious in southern Xinjiang； （6） The spatial change trend distribution was basically consistent with the regional change.
Snowfall is a critical part of the hydrological system and strongly impacted by climate change in the arid areas of Northwest China. This study uses the daily meteorological observations of 89 stations and IPCC-CMIP5 climate scenario data to estimate historical spatial-temporal variations of snowfall and extreme snowfall， mechanisms of response to climate change and future change trend across the arid areas of Northwest China. The results indicated that the annual snowfall amount shows a significant increasing trend， although the obvious decline in occurrences of snowfall during past 40 years （1971—2010）. The occurrences of extreme snowfall only accounts for smaller than 3% of that of snowfall， while contribution of extreme snowfall to annual snowfall amount accounted as high as 25%. And the increases in amount and occurrences of extreme snowfall were considered to be the main causes of the increase in annual snowfall amount. The significantly warmer temperatures （3.3 ℃） for snowfall extremes compared to other snowfall event were observed in the arid areas of Northwest China. And the mean snowfall intensity is expected to increase as temperatures when the air temperature is below 1 ℃ according to the Clausius-Clapeyron relationship. So the climate warming was considered to be the main course of the increase in extreme snowfall. The projected result indicates large reductions in the ensemble mean of occurrences of snowfall across the arid areas of Northwest China under RCP4.5 climate scenario. The annual snowfall amount will reach its tipping point at （2040±5）， while the amount and occurrences of extreme snowfall will reach their tipping point at （2060±5）. By the mid-21st century （2050s）， declines in occurrences of snowfall were projected for all stations. The mean annual snowfall amount is predicted to decrease by 5%， while the amount and occurrences of extreme snowfall have slight increases of 2% and 4% compared with the baseline period， respectively.
Permafrost regions store large amounts of soil organic carbon. Climate warming and permafrost thawing promote gradual/abrupt release of sequestered permafrost organic carbon， entering atmosphere or delivering into aquatic systems， and potentially accelerating climate warming to great extents. This paper reviews recent progress in studies on impacts of climate warming on soil organic carbon pools in permafrost regions， including permafrost organic carbon storage， bio-degradation mechanisms of permafrost organic carbon and projection of carbon feedbacks of permafrost degradation to climate warming. Results show that： Huge amount of organic carbon is stored in northern permafrost regions. Yet， its estimation is of a high uncertainty in terms of estimation for organic carbon in sub-sea permafrost and gas hydrates on continental shelves and in permafrost regions. Feedbacks of permafrost organic carbon on climate warming are regulated by soil moisture content and temperature， C/N ratio and organic carbon content， and characteristics of microbial community in soils， among many others. Model-simulated results of feedbacks of permafrost organic carbon in northern hemisphere to climate warming indicate that permafrost degradation will not result in serious socioeconomic consequences in a short term， such as before the end of the 21st century. However， both estimates on permafrost organic carbon stocks and modeling on the feedbacks of permafrost degradation to climate warming remain highly uncertain. Future predictions for feedbacks of permafrost degradation to climate warming should integrate rapid， and， particularly， abrupt thawing processes of permafrost and dissociation of hydrate carbon in modeling， such as ecological responses and sink-source strength and turnover of carbon released from small-scale thermokarsting processes. Modeling on progressive hydrothermal destabilization and rapid degradation of permafrost will provide key support for predictions， assessment， warning and management of feedbacks of permafrost degradation and permafrost carbon to climate warming.
The Third Pole and Arctic are important for environmental， social-economic， and political developments and strategies for China. It is expected to provide some experiences for the future comprehensive research by summarizing the current situation and tendency of the researches on the Third Pole and Arctic. The Third Pole and Arctic climate and cryosphere components showed significant changes， which are expected to continue in the future decades. Land air temperature in the Third Pole and Arctic warmed at twice the rate of global warming and the overall trends were highly consistent since the 1970s. The frequency of extreme events increased over the past decades. Seasonal snow cover， permafrost， land ice， sea ice， ecosystem， and hydrological cycles also showed considerable changes. These changes have not only important impacts on ecology， hydrology， and carbon cycles but also considerable impacts on infrastructure， socioeconomics， and human health. Continuously significant changes in the climate system and cryosphere may affect the globe through the amplification derived from albedo and water vapor feedbacks and a series of atmospheric circulation processes and ocean circulation processes. Currently， the common challenges of studies in the Third Pole and Arctic include extremely sparse ground monitoring networks， insufficient physics and spatiotemporal resolutions in models， and the lack of quantitative research and reliable evidence in the teleconnections within global systems. Resolving these issues mainly depends on the expansion of the ground monitoring networks and the improvements of understanding of the physics in the cryosphere and climate system. Extending from the Third Pole to the Arctic is not only the expansion of the research perspective but also important to understand their roles in the Earth system.
The temperature increases significantly in the Third Pole and the Arctic in the context of global warming. The cryosphere has a more sensitive response to climate change. Lake ice is an important part of the cryosphere in these regions. Its change is not only an indicator of climate change， but also affects the regional climate by changing the energy balance， atmospheric circulation， and radiation balance. This paper compared the advantages and disadvantages and the applicability of different observation methods， model simulation methods for lake ice. It also summarized the temporal and spatial characteristics of lake ice changes in the Third Pole and the Arctic. The results showed that lake ice in the Third Pole and the Arctic presented a delayed trend of initial ice day， early melting onset day， and shortened ice duration. The thickness of lake ice continuously decreased in the Third Pole and the Arctic. These changes in lake ice would be more significant in the future. The change of lake ice was mainly affected by temperature and also affected by temperature， restrictions on wind speed and physical and chemical properties of the lake. Besides， this article also pointed out the problems and challenges of the lake ice research and provided a scientific basis for future research in lake ice.
In the context of global climate change， snow cover in the Third Pole and Arctic region is one of the most active natural elements on the surface， and its dynamic changes have an important impact on the climate and human life. This paper reviewed the research progress of snow cover changes， and describes the distribution characteristics and trends of snowfall， Snow Covered Extent （SCE）， Snow Covered Days （SCD）， Snow Depth （SD） and Snow Water Equivalent （SWE） in the Third Pole and Arctic region. The results show that in the past few decades， especially since the beginning of the 21st century， the snowfall ratio had a downward trend； SCE， SCD， SD and SWE all showed a decreasing trend， and the snowmelt onset was earlier in the Third Pole and Arctic. At the same time， this paper discussed the impact of snow cover on ecosystems and climate systems， and then evaluated the feedback effect of snow cover. By summarizing the research progress of the Third Pole and Arctic region snow cover changes and compacting the shortcomings in the research and the future development trend， this paper provides important scientific support for further enhancing the understanding of snow cover on climate change and social and economic development.
Large quantities of organic carbon are stored in the Northern Hemisphere permafrost regions. Climate warming can accelerate permafrost degradation， one of the most significant characteristics is thermokarst. Thermokarst can directly exposes soil organic matter and change soil hydrological and biological conditions， which plays an important role in ecosystem carbon cycle. The effect of thermokarst on carbon cycle is one of the key issues to assess the uncertainties of the responses of permafrost carbon cycle to climate change. However， little is known about the effect of thermokarst formation on permafrost carbon cycle. In this paper， we review the characteristics of thermokarst landscapes and its changes in the Third Pole regions and the Arctic. Meanwhile， the effects of thermokarst on vegetation evolution， soil carbon loss and ecosystem greenhouse gas emissions were explained. Combined with the monitoring techniques of thermokarst landscapes， the challenges for studying permafrost carbon cycle are presented. Studies of thermokarst development， ecosystem carbon emission and its biogeochemical processes in permafrost regions are essential to predict the effects of climate change on permafrost carbon cycle. It will provide insights for enhancing the understanding of feedback dynamics between permafrost carbon cycle and climate warming.
Large quantities of organic carbon are stored in permafrost regions， and the change of permafrost carbon pool and the feedback of ecosystem carbon to climate change are important issues in current global climate change research. To enhance the understanding of the process of ecosystem carbon cycle， we state a comprehensive research of carbon cycle in the Third Pole and the Arctic. The size and vulnerability of permafrost carbon pools and the processes of ecosystem carbon exchange were summarized. Meanwhile， the permafrost carbon cycle involved the combined effects of air， sea and land were also analyzed. This research shows that there is greater uncertainty of carbon storage in the Third Pole and the Arctic permafrost regions. What’s more， the biogeochemical mechanisms controlling the carbon exchange of alpine ecosystems still need further studies. Under climate change scenarios， the change of permafrost carbon pool and its response to climate change is a key part in predicting future climate change.
Due to the extreme cold weather and complex environment conditions， cold damage on canals is a serious problem in cold regions， which has become a threat to water supply ability and safety. In this paper， a general overview about the relevant researches are summarized， and the future research topics are proposed， including phenomena， research methods， prevention and treatment of frozen injury. Here， the frozen phenomena mainly include the destruction of lining and insulating layer， falling off of joint sealing materials， foundation soil loss and slump and canal ice jamming and overtopping， etc. The main reasons that cause frozen injury include frost heave， freeze-thaw cycles， geologic conditions and constructive conditions， etc. Investigation is developed generally on optimal design of the lining and the coupled heat-moisture-stress analysis， etc. The prevention and treatment mainly include the replacement of foundation soil， use of insulation layer and build of drainage system， etc. However， at present， the shortcomings of the research are mainly reflected in the oversimplification of the lining stress analysis model， the lack of quantitative research on different anti-seepage and thermal insulation measures， the failure to consider the special conditions of water conveyance channels and the lack of scientific methods to extend the water conveyance time management in winter.
As an important part of China’s cryosphere， the hydrothermal condition of the permafrost on Qinghai-Tibet Plateau is an important factor affecting the ecological environment of cold regions， the exchange of water and heat between land and air， climate change and the construction of embankment. In order to enhance the understanding of the hydrothermal characteristics of the active layer in permafrost regions of the Qinghai-Tibet Plateau， this paper summarizes the main factors that affect the hydrothermal characteristics of the active layer and the main research methods， and points out the main problems in the current research. It is believed that meteorological conditions， vegetation coverage， soil properties and snow cover are the main factors affecting the hydrothermal process of the active layer. At present， researches on the hydrothermal characteristics of the active layer are mainly carried out through the in situ measured data and model simulation. The future work should focus on improving the land surface model suitable for alpine mountains and enhancing the interaction between hydrothermal dynamic processes and climate system.
The surface morphology of quartz particles in the soil is not only the information carrier of the sedimentary environment and transport mechanism from the sediment source area， but also directly affects the macroscopic physical property of the sand， which is of great significance to mechanics and practical engineering. Scanning electron microscope was used in this paper and two quantitative indexes， aspect ratio and psephicity， were used to observe two groups of sand particles subjected to different freezing-thawing cycles. It is hoped that by observing and studying the sand particles under different freeze-thaw cycles， the variation of the surface morphology of sand particles due to freezing-thawing have been summarized， which will provide theoretical basis for future studying the historical changes and paleoclimate environment in glacialized and frozen soil areas. It also provides theoretical support for the practical engineering application in seasonal frozen soil areas. It is shown that during the freezing-thawing， the psephicity of sand particles first increases， then decreases and finally tends to be stable due to the interaction among the particles. The aspect ratio first decreases， then increases， and finally stabilizes. The aspect ratio conjugates with the curve of psephicity. At the same time， during the freezing-thawing cycles， the frictional action among the particles occurs first， and then the great stress among the particles causes the particles to break down. The number of freezing-thawing cycles required for the crushing of coarse sand particles is obviously less than that of fine sand particles. With the increase of freezing-thawing cycles， the dynamic equilibrium of damage-grinding tends to be stable.
The change of Arctic river runoff could affect the sea ice thermal process and ocean thermohaline circulation. Based on the temperature， precipitation and runoff data from 1936 to 2017 provided by Global Precipitation Climatology Centre（GPCC）and Russian Hydro-Meteorological Services， the variation characteristics of climate and runoff in the Lena River Basin of Arctic over the past 80 years were analyzed， and the impacts of climate change on runoff were explored. The results suggested that the air temperature， precipitation and runoff all showed an increasing trend， with rates of 0.18 ℃·（10a）-1， 4.7 mm·（10a）-1 and 399 m3·s-1·（10a）-1， respectively. The runoff showed an upward trend in all seasons， especially in spring and winter. The increase of spring runoff was mainly caused by the acceleration of snow cover melting due to the higher temperature， followed by the replenishment of spring precipitation. The main reason for the increase of summer and autumn runoff was the contribution of increasing precipitation， higher temperature increased evaporation and reduced runoff. The increase of runoff in winter was due to the degradation of permafrost or thickening of the active layer as temperature rising， which promoted more frozen water to enter the runoff process， resulting in the increase of runoff.
The water cycle occurs on a global scale， and solutions to local and watershed water problems also often require a global perspective. Therefore， global hydrological models （GHMs） are emerging and fast-growing as a separate research field in the last two decades. In this review paper， we discuss the research significance and great potential of global hydrological modelling and observation， systematically summarize the status of the existing global hydrological models， analyze the main shortcomings and challenges of existing global hydrological models， in order to further improve the models， outlook the trend and momentum of global hydrological model development， in terms of model mechanism， big data， new technology， and the coupling of multi-sectoral models.
Based on the water samples， collected from the headwaters to Fuyun stream segment of the Irtysh River in April 2018， this study analyzed the hydrogen and oxygen stable isotopes and physicochemical indices ［including major chemical ions， pH， electrical conductivity， total dissolved solids （TDS） etc.］ by using Gibbs diagram， Piper three-line diagram and correlation matrix analysis comprehensively. Results show that river water presents weak alkalinity and belongs to low salinity water， with a mean TDS of 72.02 mg·L-1 in spring. The rank order for major ions is HCO3- > SO42- > Ca2+ > Na+ > Cl- > NO3- > Mg2+ > K+， of which HCO3-， SO42- and Ca2+ are the major anions and cations. Hydrochemical type of the river water changes from HCO3--Ca2+ to （HCO3-， SO42-）-Ca2+ from the Kuyrte River to the Fuyun stream segment of the Irtysh River. The ion content increases with flow extension and increases in touching-time with riverbed， but this process has difference due to effect of various factors. River water ions are mainly controlled by water-rock weathering， which are mainly originated from weathering and hydrolysis of carbonate rocks， weathering of feldspar minerals and downstream human activities. The δD and δ18O increase gradually along the river and enrichment phenomenon occurs in downstream.
With the rapid growth of the global economy， the improvement of transportation accessibility， the increase of public leisure time and the diverse consumer demand of tourists， glacier tourism has developed rapidly. However， with the global climate change， the sustainable development of glacier tourism has been affected in different extent. More and more researchers are beginning to focus on a series of issues such as climate change， glacier tourism， local social and ecological environment and future direction of glacier tourism. To this end， this study systematically reviewed the current development process of glacier tourism in the world through the method of literature review. At the same time， based on existing researches， the relationships of glacial tourism with cultural services， climate change， local environment， natural diseases， risk management and spatial planning are fully reviewed. The above research can provide a theoretical basis for the sustainable glacier tourism development. Especially in March 2016， General Secretary Xi Jinping pointed out the science concept of “lucid waters and lush mountains are invaluable assets， while the ice frozen areas have a lot of opportunities to gain the fortune” during the fourth session of the twelfth National People’s Congress. The affirmation and development of this concept will surely attract more and more domestic and foreign tourists to visit and experience the glacier tourism destinations in western China. The above research can provide a theoretical basis for the sustainable glacier tourism development.
Antarctic Ice Sheet is not only the sensitive indicator of global environmental changes， but its melting is also the largest uncertainty of the future sea-level rise. The numerical model is an important methodology for diagnostic ice flow mechanism and assessing ice mass loss. This paper introduces the basic principles of a new generation ice flow dynamic model， úa， based on which the two experiments are implemented to simulate the dynamics of Amery Ice Shelf （AIS） in East Antarctic. Leveraging the adaptive triangular finite-element meshes， such model solves vertically integrated formulations of the mass and momentum conservation equations. The generated mesh accurately captures the glacial dynamics from only a few parametric criteria， which reduces the computation time. On the basis of mainstream datasets， two experiments are designed in the AIS area. In the first part of the inverse run， the value of cost function in the model reduces for three orders of magnitude. Although the fine-scale structures remain to be improved， the output flow pattern agrees well with the satellite observation （RMSE = 13.35 m·a-1）. In the second part of the prognostic run， we test the sensitivity of ice thickness change rate， from which the optimal one with the minimum bias is selected to simulate the shelf’s collapse scenario. The results demonstrate the upstream ice system would contribute about （45.36 ± 0.08） mm to sea-level rise. Since Antarctic topography data were updated， whether our model can be improved from the new data deserves further research.
As a rapid， accurate and economic way for measuring soil water content， time domain reflectometry （TDR） has been widely used around the world. Appropriate TDR calibration curve （i.e.， the relationship between the soil apparent dielectric constant and soil water content） is critical for the accurate measurement of soil water content. At present， many TDR calibration curves are available in literature and the accuracy of the soil water measurement is largely determined by the choice of TDR calibration curves. However， no study attempted to systematically verify or assess their performance. The objectives of the study were therefore to collect the available empirical and semi-empirical formulas in literature， and evaluate them with a compiled high quality literature data. A total of 19 empirical models and 5 semi-empirical models were collated. Their performances were evaluated by three indices including the root mean squared error （RMSE）， average deviation （AD）， and NSE. The result showed that the formulas of Jacobsen， Topp， Roth（1992）2， Jacobosen， Yoshikawa2， Alharathi and four Malicki functions have the best performance based on NSE， AD and RMSE indices. Because of the nature of empirical models， empirical and semi-empirical TDR calibration curves can only be used for certain types of soils tested. The reader are encouraged to test or establish new calibration curves using the recommended calibration curves with new parameters for soils not mentioned in this study. The result of this study will contribute to the appropriate selection of TDR calibration curves for accurate measurement of soil water content.
Ice dams of different degrees occur almost every year in Heilongjiang River during the ice cover breaking up period， and the resulting flood causes huge losses of people’s lives and property， and anti-ice blasting is one of the main means to prevent the occurrence of ice dams. In order to ensure that ice jam flood disasters caused by ice dams do not occur when ice cover breaking up on a river， anti-ice blasting should carry out in the Huma section of the Heilongjiang River before ice cover breaking up in 2018. Through analysis of ice-water data including measured synchronously ice thickness and water depth， it was found that the narrow and slow flow channel is the potential location of ice dam and should be taken blasting measures. The relationship between the measured diameter of the blasting pit and the amount of explosive， ice thickness and water depth is analyzed， and the measured data in Huma section during blasting are brought into new equation for calculating the radius of blasting pit. The calculated value is close to the measured value， which would be useful for the anti-ice blasting in the northern cold regions.
Heat-reflective technology is widely used for effectively cooling buildings and road surfaces. Few studies have been conducted on the thermal protection of roads in permafrost regions. Based on the characteristics of climate and engineering environment in permafrost regions， this paper reviews the application and research progress of heat-reflective technology in permafrost roads. The basic compositions， heat-reflective mechanisms and testing methods of heat-reflective coatings are introduced. Meanwhile， the material property， heat-reflective performance and pavement performance of the pavement coatings are emphatically analyzed. The applications of heat-reflective coatings on embankment slopes are briefly discussed. Finally， it is pointed out that the problems encountered in the use of heat-reflective coatings to protect roads in permafrost regions under current conditions. On this basis， the focus of future research is put forward： started with material selection， theoretical analysis and test methods， improve the color， cooling performance， pavement performance and regional applicability of heat-reflective coatings， enhance the field tests of heat-reflective coatings in permafrost regions， study the coating performance under complex climate and real engineering environments.
