25 June 2018, Volume 40 Issue 3
    

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  • Temporal and spatial variation characteristics of mass balance of global reference glaciers from 1984 through 2016
    LIANG Pengbin, LI Zhongqin, ZHANG Hui, WANG Feiteng, MU Jianxin, HE Haidi
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(3): 415-425. https://doi.org/10.7522/j.issn.1000-0240.2018.0047
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    Based on the glacier mass balance data released by the World Glacier Monitoring Service, variation of 40 reference glacier mass balances all over the world were analyzed. It was found that since 1984, 36 of the 40 reference glaciers, have retreated, especially in the middle latitude regions, global glaciers have shown a trend of accelerated ablation after 2000, with a multi-year average of mass balance of -563 mm and a cumulative mass balance of -18 590 mm. The decadal mean mass balance of global reference glaciers have been descending step by step, and the mass balance declining by about 200 mm every ten years, especially from 1990 to 2010. Due to the different regional climate change and the different response of glaciers to climate, the glacier mass balance has shown significant regional characteristics and the mass balance has gradually increased from north to south, showing typical latitude and longitude features. Temperature is the main factor controlling the glacier mass balance change, the variation process of mass balance has been usually associated with climate fluctuation in each regions.
  • Distribution features of permafrost organic carbon density on different vegetation types in the upper reaches of Heihe River, Qilian Mountains
    MA Suhui, MU Cuicui, GUO Hong, ZHANG Xiankai, LI Zeyuan, ZHANG Tingjun
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(3): 426-433. https://doi.org/10.7522/j.issn.1000-0240.2018.0048
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    The heterogeneity of mountain permafrost affects the alpine vegetation type and have an effect on the distribution of soil organic carbon (SOC). In this study, the SOC densities and soil physical and chemical properties were measured on soil samples, which sampled from eight active layers within three types of vegetation cover (swamp meadow, alpine swamp meadow and alpine steppe). It was found that the average SOC density was highest in alpine swamp meadow (49.50 kg·m-2), following by alpine meadow (11.22 kg·m-2), and in alpine steppe it was the lowest (7.30 kg·m-2). In a vertical profile of SOC density, there was a slightly difference:no obvious variation in alpine swamp meadow, decreasing with depth in alpine meadow and alpine steppe, with a significant aggregation in surface. There were positive relationships between SOC density and soil moisture, silt and clay content, and a negative relationship between SOC density and pH value. General linear model result shows that the soil moisture content, pH value and soil particle composition are able to explain 96.39% of the organic carbon density variation, of which 81.53%, 9.33% and 4.75% are attributed to soil moisture, pH value and soil texture, respectively. It means that soil moisture plays a key role in distribution of SOC density in alpine permafrost regions.
  • Glacial evidence of aridification in the Tianshan Mountains since Last Glacial
    XIAO Jing, LIU Gengnian, NIE Zhenyu, CHEN Yixin, PENG Xu, LIU Beibei, HAN Yesong, CUI Zhijiu
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(3): 434-447. https://doi.org/10.7522/j.issn.1000-0240.2018.0049
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    Based on the reconstruction of paleo-glaciations and estimation of paleo-ELAs of seven study areas with precise chronological data, in this paper, the advance and recession of the glaciers in the Tianshan Maintains since the Last Glacial were revealed. Marine Isotope Stage (MIS) 4 and MIS 3 were significant periods of glacial advance with large-scale, forming compound valley glaciers and piedmont glaciers; during MIS 2, glaciers (mainly valley glaciers) still expanded significantly, but far less than before. In Neoglaciation (NG) and Little Ice Age (LIA) there were slight expansion of glaciation, showing their terminal moraines had distributed in front of contemporary glaciers and the glacier types were the same as present. The decreasing amplitude of ELA had shown a parallel pattern:with a maxima decline during MIS 4 and MIS 3, and a progressively diminishing decline since MIS 2. The great glacial expansions in MIS 4 and MIS 3 in the Tianshan Mountains were related to more moisture being transported into by the westerlies from ice-dammed lakes and wet lands formed by the Eurasian Ice Sheets. Since MIS 2, the recession of Eurasian Ice Sheets, the decrease in moisture from westerlies and the gradually strengthening Mongolian High may have resulted to glacier shrinkage.
  • Various levels of cold air in Xinjiang Region from 1961 through 2016:climatic characteristics and variation
    JIANG Yuan'an, YIN Yizhou, FAN Jing, LIU Jing, JIA Zila, YU Xingjie
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(3): 448-460. https://doi.org/10.7522/j.issn.1000-0240.2018.0050
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    Based on the daily minimum temperature data of 89 national meteorological stations from January 1961 to February 2017, within the single station cold air rate according to the Cold Wave Level (GB/T 21987-2008) and Cold Air Grade (GB/T 20484-2006) in the National Standard of the People's Republic of China and the Cold Air Process Monitoring Index (QT/T 21987-2008) in the People's Republic of China Meteorological Industry Standard, we applied of linear trend, EOF decomposition and other analytical methods, and calculated the occurrence frequency, temperature drop and continuous days of the cold wave process of Xinjiang in the past 56 years, and the temporal and spatial distribution characteristics of the single-station cold wave in Xinjiang were analyzed. The results show, 1) Xinjiang single station different levels of cold air annual average frequency and the cumulative number of days are the medium cold air up, the second most cold wave, strong cold air at least, spatial distribution characteristics were presented in northern Xinjiang more, southern Xinjiang less. 2) The annual mean frequency and annual cumulative number of medium strength and strong cold air showed no significant decrease trend, interannual fluctuations are more obvious. 3) Medium strength and strong cold air in the early fall and late spring occurred more, cold wave occurred in the winter more. 4) The cumulative temperature drop of the cold air above the medium strength are showing the distribution characteristics of the northern Xinjiang more, southern Xinjiang less, and the distribution of the regional average is significantly reduced. 5) The first mode of annual cold wave frequency and accumulative temperature drop were 33% and 39%, far more than other mode, and their spatial distribution of the first mode were expressed as a positive value for the whole of Xinjiang, and the characteristic value of northern Xinjiang is larger than southern Xinjiang, indicating that their trends are consistent with the characteristics of the trend, while the northern Xinjiang is more prone to abnormal, southern Xinjiang is not easy to abnormal. Prior to the 1980s, their coherence interannual variability was mainly for positive phase, indicating that there is much more likely to be consistent, since 2000, the time coefficient is mainly in the negative phase, indicating that there is less coincidence.
  • Study on spatial distribution pattern of the soil organic carbon in winter rangeland of Maqu, Qinghai-Tibet Plateau
    YANG Shurong, ZHANG Jian, CHEN Shuzhen, CAO Jianjun
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(3): 461-468. https://doi.org/10.7522/j.issn.1000-0240.2018.0301
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    The total of 60 sites were selected to analyze the characteristics of the spatial distribution of SOC in winter rangeland of Maqu, Qinghai-Tibet Plateau. The stratified sampling method was taken to a depth of 30 cm using soil control sections (S1:0~15 cm; S2:15~30 cm). The results showed that, SOC of the north (including northwest) and southeastern regions (the average SOC were 58.78 g·kg-1 and 45.78 g·kg-1) are the higher in the aspect of horizontal distribution. However, SOC of the eastern (including northeast) and central of Maqu was lower due to heavy grazing, about 39.65 g·kg-1 and 38.32 g·kg-1 respectively. In the aspect of vertical distribution, the SOC decreased with the depth of soil, and the SOC of 0~15 cm is about 53.39%~70.61% of its surface (0~30 cm). From this study, we could conclude that the northern and southeastern regions in Maqu should be given priority protection, and over-grazing should be strictly prohibited, especially those activities that may cause more severe damage to the surface of the soil. Meanwhile, both the upper and the lower soils should be considered in grassland management and soil nutrient balances. In addition, the existing multi-household grassland management should be retained, and that single-household grassland management should be encouraged to reunite into the multi-household grassland management, because it is also conducive to protect the soil in this area.
  • Soil quality assessment of alpine grassland in permafrost regions of Tibetan Plateau based on principal component analysis
    LIU Xin, WANG Yibo, LÜ Mingxia, SUN Yan, YANG Wenjing, ZHAO Jinpeng
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(3): 469-479. https://doi.org/10.7522/j.issn.1000-0240.2018.0052
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    Soil quality assessment is a key step for comprehending soil quality. In order to understand the soil quality of the alpine grassland in permafrost regions of the Tibetan Plateau, 154 soil samples were collected from different altitudes and different vegetation coverages from Xidatan to Anduo in the hinterland of the Plateau. Principal component analysis (PCA) was employed to determine the minimum data set (MDS):total nitrogen, total phosphorus and total potassium, which affected the soil quality on the Plateau. The soil quality of alpine grassland in permafrost region of the Tibetan Plateau was evaluated according to the MDS of soil quality, and the soil quality index (SQI) was obtained under different altitudes and vegetation coverages. The comparative study of the soil quality index under different vegetation coverages and different altitudes showed that SQI increases with increase of vegetation coverage, that is to say, SQI in altitude range of 4 300~4 600 m(0.270±0.043)
  • The influence factors of permafrost active layer depth and their annual change in Heilongjiang Province
    YOU Mingdong, LI Haibo, GE Min, ZANG Shuying
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(3): 480-491. https://doi.org/10.7522/j.issn.1000-0240.2018.0053
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    Permafrost active layer is the most active area of water and heat exchange in the stratum of permafrost and is very sensitive to climate and environmental change. Permafrost active layer in Heilongjiang Province is influenced by a variety of factors because of the unique climate. By using gray correlation degree, correlation analysis, trend degree test, vector autoregressive model, it is found that:(1) In general, seasonal depth is in close relationship with surface water content and vegetation. (2) In light of the annual variation of seasonal frozen depth, it is negatively correlated with snow, vegetation and latent heat flux and has a significant negative correlation in different regions. (3) It is positively correlating with the sensible heat flux, and Significantly in some areas. (4) In the past 30 years, the frozen layer depth and other factors has showed different trends; the change of the frozen depth has been affected by the latent heat, the surface water content, the vegetation, the heat and the snow depth; particularly, the contribution of latent heat to the long-term variation of seasonal frozen depth has reached 35.09%. This phenomenon may be caused by the unique and complex geographical environment in Northeast China and the variation of various factors in the past 30 years.
  • Analysis of the climate characteristics of snowfall in southeastern Shandong Province from 1961 to 2015
    LU Guirong, YANG Chengfang, CHENG Pan, LÜ Xiangjuan, DING Fan
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(3): 492-500. https://doi.org/10.7522/j.issn.1000-0240.2018.0054
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    Based on the daily precipitation, daily weather phenomenon and snow cover depth data from 18 meteorological stations in southeastern Shandong Province from 1961 to 2015, the climatic characteristics of snowfall in the recent 55 years were analyzed. The results showed that the spatial distribution of annual snowfall days, heavy snowfall days, snowfall, extreme snowfall, snow cover depth and maximum depth of snow cover in mountain areas were more than that in plains and coastal areas in southeastern Shandong Province, with an obvious regional difference. Before the 2000s, there had been a snowy period, followed by a less snowy period. From 1961 through 2015, the average number of snowfall days, heavy snowfall days, extreme snowfall, snow cover depth and maximum depth of snow cover had been decreasing, the turning year from more to less of snowfall was in 1993 and snow depth, maximum depth of snow cover was in 1987, 1986. Snowfall in the southeastern Shandong Province had been mainly concentrated in January and February, with the maximum extreme snowfall in March. The month of maximum average snow depth and maximum depth of snow cover occurred in November and March, respectively. The snowfall period was from October 23 to April 28; the early beginning date and the ending date of snowfall always occurred in the northwest mountains. There was a period of 3 years in the variation cycle of snowfall days, heavy snowfall days, snowfall, extreme snowfall and snow depth, and there was a period of 4~5 years of maximum depth of snow cover.
  • Study on the synoptic characteristics of snowstorm in Hulunbuir from March 31 to April 2nd, 2016
    WANG Hongli, FU Yanan, MENG Xuefeng, SUI Hangrui, WANG Ying
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(3): 501-510. https://doi.org/10.7522/j.issn.1000-0240.2018.0055
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    In order to summarize the special characteristics of snowstorm and to make snowstorm forecast, the circulation situation and genetic mechanisms of a snowstorm weather process from March 31 to April 2nd, 2016, in Hulunbuir were analyzed using conventional observation data and NCEP 1.0°×1.0°reanalysis data. A detail analysis was done of the development of the impact systems in high and low altitude, especially, the water vapor transport conditions, water vapor convergence, local water vapor accumulation and vertical motion in the case of extreme precipitation from the perspective of synoptic meteorology. It was found that the snowstorm was confined by short wave perturbation superposed low altitude frontal zone, resulting in the release of baroclinic effective potential energy into perturbation kinetic energy and causing the disturbance to develop into large eddy. Water vapor transport effect was determined by the distribution pattern of specific humidity flux to some extent. The distribution of uniform strip had higher efficiency of transporting water vapor. Eddy differential advection and temperature advection indicated that dynamic factor and thermodynamic factor had significant contribution to vertical motion. While horizontal divergence reflected the intensity and distribution of vertical motion, as a direct parameter of quality accumulation and loss. As a physical quantity directly related to precipitation intensity, the whole layer of specific humidity flux divergence integral accurately reflected precipitation magnitude, and accurately judged the precipitation area and period with low air flow intensity and direction.
  • The establishment of NDSI and snow identification model for mapping regional snow cover using FY-3A/MERSI data:a case study in Qilian Mountains
    HAN Tao, WANG Dawei, LI Lili
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(3): 511-527. https://doi.org/10.7522/j.issn.1000-0240.2018.0056
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    Medium Resolution Spectral Imager (MERSI) on board China's new generation polar orbit meteorological satellite FY-3A provides a new data source for snow monitoring in large area. As a case study, the typical snow cover of Qilian Mountains in northwest China was selected in this paper to develop the algorithm to map snow cover using FY-3A/MERSI. By analyzing the spectral response characteristics of snow and other surface elements, as well as each channel image quality on FY-3A/MERSI, the widely used Normalized Difference Snow Index (NDSI) was defined to be computed from channel 2 and channel 7 for this satellite data. Basing on NDSI, a tree-structure prototype version of snow identification model was proposed, including five newly-built multi-spectral indexes to remove those pixels such as forest, cloud shadow, water, lake ice, sand (salty land), or cloud that are usually confused with snow step by step, especially, a snow/cloud discrimination index was proposed to eliminate cloud, apart from use of cloud mask product in advance. Furthermore, land cover land use (LULC) image has been adopted as auxiliary dataset to adjust the corresponding LULC NDSI threshold constraints for snow final determination and optimization. This model is composed as the core of FY-3A/MERSI snow cover mapping flowchart, to produce daily snow map at 250m spatial resolution, and statistics can be generated on the extent and persistence of snow cover in each pixel for time series maps. Preliminary validation activities of our snow identification model have been undertaken. Comparisons of the 104 FY-3A/MERSI snow cover maps in 2010-2011 snow season with snow depth records from 16 meteorological stations in Qilian Mountains region, the sunny snow cover had an absolute accuracy of 92.8%. Results of the comparison with the snow cover identified from 6 Terra/MODIS scenes showed that they had consistent pixels about 85%. When the two satellite resultant snow cover maps compared with the 6 supervise-classified and expert-verified snow cover maps derived from integrated MERSI and MODIS images, we found FY-3A/MERSI has higher accuracy and stability not only for nearly cloud-free scenes but also the cloud scenes, namely, FY-3A/MERSI data can objectively reflect finer spatial distribution of snow and its dynamic development process, and the snow identification model perform better in snow/cloud discrimination. However, the ability of the FY-3A/MERSI model to discriminate thin snow and thin cloud need to be refined. And the limitation, error sources of FY-3A/MERSI snow products would be assessed based on the accumulation of large amounts of data in the future.
  • Analysis on the cooling performance properties of block-stone embankment in permafrost regions under the scenario of aeolian-sand
    HAN Fenglei, ZHANG Xuefu, YU Wenbing, WEI Liangwen, ZHOU Jie
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(3): 528-538. https://doi.org/10.7522/j.issn.1000-0240.2018.0057
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    The fragile ecosystems and human engineering activities in the Tibetan Plateau aggravate the desertification along the linear engineering of Qinghai-Tibet Engineering Corridor. Therefore block-stone embankment in permafrost regions faces increasing severe aeolian sand hazard. In this paper, cooling performance and long-time thermal stability of block-stone embankment with high-grade pavement under the scenario of aeolian sand were analyzed. The results showed that permafrost temperature is more easy to be affected by accumulation of aeolian sand for closed block-stone embankment by comparing the permafrost table under the center of permafrost embankment. Wet sand of 1.0 m depth can reduce permafrost temperature, while dry sand of 0.2 m depth can rise permafrost temperature. Permafrost temperature is more sensitive to water content of sand as compared with the sand deposit depth. Under the circumstance of climate warming, the impact of sand deposit on permafrost table of embankment will weaken with the mean annual air temperature decreasing. The dry sand increases the thawed depth of permafrost, and the wet sand raises permafrost table. Permafrost table beneath the center of embankment is more sensitive and the impact of accumulation of sand weakens together with the decrease of ice content of permafrost. When the mean annual air temperature is lower than -5.5℃, closed block-stone embankment for high-grade highway could keep artificial permafrost table within the rock layer in the condition of climate warming and aeolian sand deposit.
  • Experimental study on temperature threshold for warm frozen sand in terms of mechanical properties
    GUO Xueluan, QI Jilin, DANG Boxiang, DONG Zhaoren
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(3): 539-545. https://doi.org/10.7522/j.issn.1000-0240.2018.0058
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    Mechanical properties of warm frozen soils are similar to that of unfrozen soils. Recently, the mechanical properties of warm frozen soils have been extensively studied, including strength criteria, compression feature and constitutive models. However, there is no definition of warm frozen soil according to the mechanical behavior of frozen soils so far. This paper attempts to define the temperature threshold for warm frozen sand in terms of mechanical properties. The Chinese ISO standard sand was taken as study object. Triaxial and confined compression tests were carried out. Mechanical properties such as, cohesion, modulus and compressibility index were obtained and their changing tendency along with temperature were analyzed. It is found that the range of -1.0℃ to -0.5℃ seems to be the temperature when the mechanical properties change abruptly. Therefore, -1.0℃ can be defined as the temperature threshold for warm frozen soils with regard to the material tested in this program. The research is of great significance to construct and maintain the engineering in warm frozen soils.
  • Study on damage identification of loess microstructure and macro mechanical response under freezing and thawing conditions
    YE Wanjun, LI Changqing, DONG Xihao, LIU Zhongxiang, PENG Ruiqi, WANG Yan, WU Yuntao, SUN Ruiliang, WEI Wei
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(3): 546-555. https://doi.org/10.7522/j.issn.1000-0240.2018.0059
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    The deterioration of the physical properties of loess under freezing and thawing conditions is one of the concerns that must be taken into consideration when construction in the cold regions. In this paper, a variety of loess samples with different water contents were taken from Huangling County of Yan'an Prefecture as research objective to further study the physical change of the loess while exposing in freezing-thawing environment. The microstructure alternations of loess under freezing and thawing condition were evaluated by means of scanning electron microscope, edge detection and quantitative classification; the correlationship between the moisture content of the samples and various freezing-thawing cycles were revealed, as well as the changes of strength index of the samples through GDS and its degree of significance. The results showed that the grain fracture grows with the increase of freezing thawing cycles, the large particles are continuously broken down into smaller particles, the skeleton connection mode changes from surface to surface contact to point to point contact; with the increase of the number of freezing-thawing cycles, the fractal dimension increases; after 10 freezing-thawing cycles, the porosity and fractal dimension tend to be stable; with the increase of freezing-thawing cycles, the cohesion of the sample decreases, the internal friction angle increases continuously, and the strength index tends to be stable after 10 freezing and thawing cycles. The experimental results are consistent with the scanning results of SEM; by analyzing the cohesion and internal friction angle of specimens, it can be seen that the freezing-thawing cycles, initial water content and their interaction (coupling action) have particularly significant effects on the strength index of the samples.
  • Direct shear tests of interface between salinized frozen soil and concrete lining
    SUN Zhaohui, BIAN Hanbing, LU Xiangyu, ZHANG Saize, QIU Xiumei
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(3): 556-562. https://doi.org/10.7522/j.issn.1000-0240.2018.0060
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    The study of interface between soil and structure has been one of the hot spots in geotechnical engineering research. In order to study the frost damage of canal system in Weishan irrigation district, under the conditions of different salt species, different salt content and different water content, a series of direct shear tests for frozen interface between saline soil and concrete lining have been performed to study the mechanical properties of the frozen interface. The results show that failure model of frozen interface was brittle and an obvious peak stress could be observed. The shear deformation includes linear deformation and nonlinear deformation. The linear deformation decreases with the increase of water content and salt content, and the nonlinear deformation increase with the increase of salt content. The shear modulus increases with the increase of water saturation and decreases with the increase of NaCl concentration. The shear strength increases with the increase of water saturation, decreases as the salt content increases with NaCl, while it decreases first and increases as the salt is Na2SO4. Through the strain energy analysis, it is found that the characteristics of frozen interface with water content w=14.7% and w=16.7% are similar, that means when the NaCl content is 0.5% the shear strength is minimum.
  • Study on frost resistance and damage model of steel fiber reinforced coal gangue concrete
    QIU Jisheng, PAN Du, GU Shuancheng, GUAN Xiao, ZHENG Juanjuan, ZHANG Chenghua
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(3): 563-569. https://doi.org/10.7522/j.issn.1000-0240.2018.0061
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    In order to study the frost resistance of steel fiber reinforced coal gangue concrete, the freezing-thawing cycle number and the steel fiber content are taken as the main variables. Through rapid freezing-thawing test, the change of apparent morphology, mass loss, relative dynamic elastic modulus and compressive strength of the coal gangue concrete with different dosages of steel fiber was studied. According to the change of dynamic modulus of elasticity of steel fiber reinforced coal gangue concrete, the damage variable is defined firstly, and then the damage model of steel fiber reinforced gangue concrete under freezing and thawing environment is established. The results show that in the freezing-thawing environment, adding appropriate amount of steel fiber can reduce the loss of mass and the relative dynamic modulus of elasticity, and then can improve the frost resistance of coal gangue concrete. The steel fiber reinforced coal gangue concrete damage equation has accorded well with the experimental data, which can provide theoretical reference for studying the durability of steel fiber reinforced coal gangue concrete in freezing-thawing environment.
  • Study on the permittivity mixing model of freezing soil
    JIN Xiao, YANG Wen, ZHAO Jianqi
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(3): 570-579. https://doi.org/10.7522/j.issn.1000-0240.2018.0062
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    Permittivity is the most important and basic parameter in microwave radiative transfer theory. The frozen soil studied in this paper refers to the soil containing ice at the average temperature below -4℃. In this paper, a new permittivity mixing model for microwave frozen soil has developed, in which the effects of soil temperature, frequency, soil texture and unfrozen water content have taken into account. The new permittivity mixing model uses a point method to calculate the unfrozen water content, uses Stern-Gouy double layer theory to calculate permittivity of unfrozen water, uses Maxwell-Garnett mixing theory and mixing permittivity volume theory to establish dielectric constant mixture model of frozen soil. Comparison and analysis of the theoretical and experimental dielectric constants showed that curves of the imaginary part and real part of the model agree well with the experimental results, respectively. The comparison results are satisfactory and the reliability of the model is proved.
  • Application of different filters in soil moisture assimilation
    FU Xiaolei, YU Zhongbo, DING Yongjian, YANG Chuanguo, JIANG Xiaolei, JU Qin
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(3): 580-587. https://doi.org/10.7522/j.issn.1000-0240.2018.0063
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    To study the performances of different filters in soil moisture assimilation and the model parameter sensitivity to soil moisture simulation, the assimilation and sensitivity experiments were developed. First, the sensitivity of soil saturated hydraulic conductivity (Ks) to soil moisture simulation results was analyzed based on simple biosphere model (SiB2). Then, the hourly in-situ observations were assimilated into SiB2 by ensemble Kalman filter (EnKF), unscented Kalman filter (UKF) and unscented particle filter (UPF) based on the sensitivity analysis results. The results show that:(1) soil saturated hydraulic conductivity can affect the soil moisture simulation accuracy significantly; (2) all the three filters can improve the soil moisture simulation results significantly; (3) the performances of the three filters are different at different soil layers:at soil surface layer, EnKF performs better than UKF and UPF, at root zone layer and deep soil layer, the performances of the three filters are different before and after precipitation. Thus, selecting a suitable data assimilation method is an efficient way to improve the soil moisture simulation accuracy.
  • The characteristics of high-speed railway subgrade's temperature, moisture and frost heave deformation in high altitude and seasonal frozen region:taking the Minle section of Lanzhou-Xinjiang passenger railway line as an example
    SHAO Zhujie
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(3): 588-597. https://doi.org/10.7522/j.issn.1000-0240.2018.0064
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    The Lanzhou-Xinjiang Railway Second Double Line is the first and the longest high-speed railway in the high altitude and seasonal frozen areas in Northwest China. Based on the observation at three monitor sections, wide-spread frost heave had been captured over two freezing periods (2015-2017). The results showed that the heave mainly occurred in the coarse fills that have been ever considered as unsusceptible to frost heave. The frozen period was nearly five months and the maximum frozen depth ranged from 3.0 to 3.8 m, two times of original frozen depth. The maximum frost-heave amount can reach to 27.5 mm between the surface and a depth of 2.7 m. The water content in crushed rock layer (0~0.5 m) is less than 4% in warm reason, and decreases in cold reason. The water content in coarse soil layer (under 0.5 m depth) is relative higher, between 8% and 15%, and the water content in warm reason is lower than that in cold reason, distributing as a sine curve. With the depth increasing, the water content decreases gradually. The development process of frost heave can be divided into three linear phases, and the maximum growth rate of frost-heave amount occurs from the middle or last ten days of December to the middle ten days of January, which means that in about twenty days in all a stable frost-heave amount will be reached.
  • Extreme climate research on Gulang River basin in eastern Qilian Mountains during 1960-2012
    WANG Tingting, FENG Qi, LI Zongxing, LI Jianguo
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(3): 598-606. https://doi.org/10.7522/j.issn.1000-0240.2018.0065
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    The increasing extreme climate events at the global scale are causing a series of scientific and societal issues under the background of global warming. The variations of daily temperature and precipitation of Gulang River basin in eastern Qilian Mountains showed that increasing frequency and amplitude of growing season length (GSL), summer days (SU25) and consecutive warm days (CWD) as well as prominent warming indicated the good response to global warming. The quasi-3-year and quasi-8-year periodicities of precipitation in whole basin were identified by wavelet analysis. Extreme wet day precipitation (R95P) is becoming more contribution for annual precipitation, but the simple daily intensity index (SDⅡ) presented regional diversity. The consecutive dry days (CDD) revealed that humidification is going prominent. This work provided the science and technology support to water source and ecological services in Gulang River basin.
  • Study on vertical gradient change of air temperature and precipitation in Vrümqi River basin during 1961-2016
    LI Kaiming, ZHONG Xiaofei, JIANG Ye, LI Jianing, LI Linfeng, ZHOU Ping
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(3): 607-615. https://doi.org/10.7522/j.issn.1000-0240.2018.0066
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    There are great differences in climate change between high mountains and plains in the Vrümqi River basin of Xinjiang. Researching the vertical gradient variations of air temperature and precipitation in this regions may be useful for knowing the interaction process among various geographical factors. Based on the observation in the Vrümqi River basin, the change trend of air temperature and precipitation, the relationship between air temperature, precipitation and its inclination rates with altitude are analyzed in this paper. The results showed that the air temperature and precipitation had increased from 1961 through 2016. The inclination rates of air temperature and precipitation in Daxigou Station were 0.189℃·(10a)-1 and 28.83 mm·(10a)-1, respectively, and those in Vrümqi Station were 0.268℃·(10a)-1 and 18.85 mm·(10a)-1, respectively. Air temperature and precipitation have close relationship with altitude; air temperature gradually increases and precipitation decreases as elevation decreasing. The inclination rate of air temperature in high altitude is larger than that in lower elevation, while it is reverse for that of precipitation. The curve of monthly air temperature inclination rate varying with elevation shows down~up~down~up, with a peak during ablation period. The value of precipitation inclination rate shows slightly descending~dramatically ascending~dramatically descending~slightly ascending, and reaching the maximum in summer.
  • Quantitative assessment of land use change impacting the vegetation index in the arid regions of Northwest China
    JIANG Yuqing, LI Baofu, SONG Meishuai, JIAO Jianfei, LIU Wenqing
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(3): 616-624. https://doi.org/10.7522/j.issn.1000-0240.2018.0067
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    Under the background of global change, distinguishing the impact of human activities and climate fluctuation quantitatively is of great significance to vegetation growth in the arid regions. In this paper, using a variety of statistical methods, the spatial and temporal variation characteristics of the land use/cover change (LUCC) from 1990 through 2010 and the normalized difference index (NDVI) from 1982 through 2010 in the arid regions of Northwest China are analyzed, and the LUCC effects on NDCC change are quantitatively evaluated. The results are as follows:(1) One of the fastest growth was arable land, up to 13 476 km2, followed by forest lands and waters; the area increased mainly from grassplot (12 590 km2) and unused land (6 025 km2) from 1990 to 2000. (2) The rate of change of various land types were as follows:arable land > construction land > waters > woodland > grassplot > unused land. (3) The land-using degree index (0.79) in the study area from 2000 to 2010 was significantly higher than it from 1990 to 2000 (0.23), showing that the influence of human activities on land use has markedly enhanced in recent years. (4) The NDVI had increased from 1982 to 2010, but in recent years (2002-2010) it had decreased slightly. Specifically, the contribution of LUCC on NDVI had been relatively low from 1990 to 2000, only 2.9%; even so, the contribution from 1990 to 2010 had been 26.7%, showing the contribution of climate change on vegetation index change up to 73.3%.
  • Study on the low water consumption patterns from the perspective of water footprint:take Zhangye Prefecture residents' food consumption as a case
    SU Fang, SHANG Haiyang, DING Yang
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(3): 625-633. https://doi.org/10.7522/j.issn.1000-0240.2018.0068
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    Population growth, technology stepping forward and increasing consumption are considered to be the main causes of the three environmental crises. Environmental problems due to population growth and technology stepping forward have already caused widespread concern, while the environmental problems caused by consumption increase have not gotten enough attention and research in-depth. In this paper, the water footprint theory is proposed to discuss the necessity and to advocacy meeting basic human needs while reducing the water footprint consumption. Then, a healthy dietary pattern (DGE) recommended by the German Nutrition Society is taken as a reference, as well as the Australia daily dietary consumption patterns. There are difference among the counties of Zhangye Prefecture in diet type. The food consumption, consumption of water footprint components and water footprint characteristics of total consumption in the structures of three consumption are analyzed. According to the study, the following conclusions can be drawn that compared with the DGE health model, the consumption of eggs and meat is higher in the counties (district) of Zhangye Prefecture, while the consumption of vegetables and fruits is lower; from the point of the total water footprint consumption, only Linze County, and Shandan County are close to DGE health model, Sunan County is higher than the DGE health model; compared with healthy patterns DGE water footprint diversity, Linze County's diversity index (1.82) is close to DGE health model's diversity index (1.84). Among the counties of Zhangye Prefecture, Linze County will go through adjusting the current diet, firstly realizing the healthy consumption patterns recommended by German Nutrition Society and the low water consumption patterns from the perspective of water footprint.
  • Ecological security assessment of Hubei Province based on the emergy-ecological footprint model
    FENG Fang, JIN Shuang, HUANG Qiaohua, DAI Guibin, ZHANG Tao
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(3): 634-642. https://doi.org/10.7522/j.issn.1000-0240.2018.0069
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    Based on the emergy-ecological footprint model, the ecological security of Hubei Province was quantitatively evaluated from 1997 to 2014. The results revealed that the average annual emergy density in Hubei Province was calculated as 1.286 1015 sej hm-2 during the study period. The emergy ecological capacity per capita slowly decreased from 1.18 hm2 to 1.10 hm2, with the average value of 1.12 hm2, while the emergy ecological footprint per capita rapidly increased from 4.50 hm2 to 8.72 hm2, with the average value of 6.26 hm2. The ecological footprint per capita has been increased with a growth of 6.2% since 1998, which caused a trend gradually increase of the ecological deficit. Hubei Province has been in a state of ecological deficit since 1997 and the situation was gradually getting worse. Therefore, the ecological environment system was insufficient to maintain rapid economic and social development. The ecological pressure index increased from 3.82 to 7.95, which suggested the problems in ecological safety needed to be solved urgently. The giant pressures from the urban construction and the heavy industry with high-level energy consumption, as well as the sharply increase of the total export-import volume, were the principal factors, which prompted the growth of the local ecological deficit.
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