25 August 2013, Volume 35 Issue 4
    

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  • WANG Zhi-lan, WANG Xiao-ping, LI Yao-hui
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 783-792. https://doi.org/10.7522/j.issn.1000-0240.2013.0089
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    Reliability of snow cover data is the key factor to reflect the change of snow cover and to predict the climate change. Based on the observed snow data from 74 weather stations, the snow data accuracy from passive microwave remote sensing over the Tibetan Plateau was analyzed. The results show that both passive microwave remote sensing data and observed data reveal high seasonal snow cover regions in the southwestern edge of the plateau and in the east of the Tanggula Range and the Nyainqêntanglha Range. Less seasonal snow cover regions are the Qaidam Basin and the hinterland of the plateau and along the Yarlung Zangbo River. Snow cover has a significant difference between the south of Qinghai Province and the southeast of the plateau. There is a good consistent between passive microwave remote sensing data and observed data in significant seasonal characteristics and annual variations of snow cover. However, the remote sensing data do not describe the fluctuating characteristics within a season very well. Annual mean snow depth derived from passive microwave remote sensing data seems larger than that from weather station's data. Looking from the daily snow depth data of AMSR-E, it is found that the accuracy of snow cover in the plateau hinterland is higher than that in the plateau margin. Also, the accuracy is higher in the regions below 3 000 m a.s.l. and when snow depth is 9~10 cm.
  • HU Lie-qun, LI Shuai, LIANG Feng-chao
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 793-800. https://doi.org/10.7522/j.issn.1000-0240.2013.0090
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    Based on the meteorological data from 91 stations in Xinjiang from 1960 to 2011, the number of days with snow cover, the maximum snow depth, and snow beginning date and ending date are analyzed. The spatial distribution of maximum snow depth is calculated by the Kringing interpolation. The results show that snow is mainly distributed in the north of the Tianshan Mountains. Its depth can reach more than 30 cm. Snow depth in the south of the Tianshan Mountains is relatively small, mostly less than 10 cm in winter and spring. Snow depths in North Xinjiang, South Xinjiang and the Tianshan Mountains have increased slightly in recent 50 years (especially in the Tianshan Mountains). However, the number of days with snow cover has decreased slightly, and the snow beginning date and ending date have changed insignificantly. It is found that the correlation of snow cover change is significant between the Tianshan Mountains and North Xinjiang, with a correlation coefficient of 0.708 for snow depth and that of 0.614 for number of days with snow cover. It seems no significant correlation of snow cover change between South Xinjiang and the others. Snow depth is positively correlative to precipitation, with a correlation coefficient of 0.702 in North Xinjiang. There is a good negative correlation between the number of days with snow cover and air temperature, with a correlation coefficient of 0.742 in North Xinjiang, but there is no obvious correlation between the number of days with snow cover and precipitation in winter and spring.
  • BIN Chan-jia, QIU Yu-bao, SHI Li-juan, Chuduo, ZHU Ji
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 801-813. https://doi.org/10.7522/j.issn.1000-0240.2013.0091
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    Using passive microwave data to derive snow depth has become a fast and effective method, but regional accuracy of global snow algorithms is limited, especially in the regions where ground-based measured data are short, such as west China and the Tibetan Plateau. In this study, for the sake of evaluating the accuracy of snow inversion algorithms by using passive microwave data from the Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) in China, five different snow algorithms (Chang algorithm, Goddard Space Flight Center, GSFC, 96 algorithm, AMSR-E SWE algorithm, improved Tibetan Plateau algorithm and Savoie algorithm) are selected, making use of AMSR-E brightness temperature data and meteorological station data in February 10-12, 2010, to validate the accuracy of snow depth algorithms in Xinjiang, the Tibetan Plateau, Inner Mongolia, Northeast China, Northwest China, the North China Plain, and then compared the accuracies of the five snow inversion algorithms. It is found that in the overall validation, the results of improved Tibetan Plateau algorithm are better than other algorithms, of which the root mean square error (RMSE) is 9.16, 9.96 and 9.63 cm;the average relative error (MRE) is 59.77%, 52.79% and 48.47%. In the partition validation, the results of the best algorithms are: in Xinjiang, with the RMSE of GSFC 96 algorithm ranging from 6.85 to 7.48 cm;in Inner Mongolia, with the RMSE of the improved Tibetan Plateau algorithm of 5.9, 6.11 and 5.46 cm;in Northeast China, with the RMSE of improved Tibetan Plateau algorithm ranging from 6.21 to 7.83 cm;in the Tibetan Plateau, owing to the lack of measured data, the verify statistical result is unable to obtain;and the existing algorithms have a poor applicability in Northwest China and the North China Plain.
  • LIU Wei-gang, XIAO Cun-de, LIU Jing-shi, SHEN Yong-ping, ZHANG Dong-qi, LIU Jing-feng, ZHANG Tong, HOU Dian-jiong, LIN Xia
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 814-823. https://doi.org/10.7522/j.issn.1000-0240.2013.0092
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    Based on the ablation data obtained in 1959 and 2009, ablation rates of the Rongbuk Glacier, a debris-covered glacier located on the northern slopes of the Mt. Qomolangma, were analyzed in this paper. Debris thickness decreased along with altitude. Ablation rates varied considerably with various thicknesses of debris. When debris thickness was larger than 8.5 cm, glacier ablation rate decreased with the increasing thickness of debris. The threshold debris thickness which could accelerate the glacier melting was larger than 5 cm. Both temperature and debris thickness comprehensively controlled the glacier ablation rate, which could be illustrated in detail as follows: In the low and high parts of this debris-covered glacier, ablation rates were both relatively lower since thicker debris and lower temperature at these two parts mentioned above suppressed glacier ablation, resulted from less energy supplied to the melting front;Nevertheless, in the middle part of the glacier, thin debris together with relatively high temperature led to higher glacier ablation rate. Ablation rate was less than 20 mm·d-1 in most parts of the glacier with a maximum ablation rate at the altitude range of 5 400~5 450 m a.s.l. Daily ablation rate was positively correlated with daily mean temperature. Glacier ablation rate in the southern Himalayan was larger than that in the northern Himalayas.
  • HONG Tao, LIANG Si-hai, SUN Yu, ZHAO Zhen-wei, HAO Yu-pei, WANG Xu-sheng, WAN Li
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 824-833. https://doi.org/10.7522/j.issn.1000-0240.2013.0093
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    Analyzing the heat conductivity coefficient within the active layer in permafrost is of scientific value for understanding the permafrost response to global climate change and their impact on environment. Dry bulk density, water content and temperature were related to heat conductivity coefficient of three typical soils in the headwaters of the Yellow River and found that dry bulk density and water content are the major factors controlling the heat conductivity coefficient but the relation between temperature and heat conductivity coefficient is not obvious. Employing Stephen function and GIS software, based on the measured heat conductivity coefficients, the maximum thawed depths and maximum frozen depths in 2002 were simulated. The Simulation shows that the maximum thawed depth at the low altitude, such as the Yellow River and Gyaring and Ngoring Lakes, is greater than that at the high altitude, such as the Buqingshan Mountain and Bayan Har Mountains. On the contrary, the maximum frozen depth at the low altitude is less than that at the high altitude. Comparing the maximum thawed depth and the maximum frozen depth, it is found that most permafrost is undergoing degradation, except for a small part in the north. The findings of this study may have a broad implication for assessing the variation of permafrost and ecological environment due to climate change.
  • LIU Yu-shuo, QIN Xiang, DU Wen-tao, ZHANG Xue-yan, CHEN Ji-zu, XIE Xiao-long, ZHANG Xiao-peng
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 834-840. https://doi.org/10.7522/j.issn.1000-0240.2013.0094
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    In September 2009, the expedition established a geodetic chain around the Ningchan River Glacier No. 3, and 13 mark points were installed on the glacier surface for surveying glacier flow velocity. In July 2010 and September 2010, the mark points were surveyed again and again, and the surface flow velocities of the glacier were determined for the periods of 2009/2010, September 2009-July 2010 and July 2010-September 2010. It is found that the maximum surface flow velocity was 3.76 m·a-1 (at the elevation of 4 430 m) for the periods of 2009/2010, 0.32 m·month-1 (at the elevation of 4 430 m) in the time bucket from September 2009 to July 2010 and 0.47 m·month-1 (at the elevation of 4 380 m) in the time bucket from July 2010 to September 2010. Overall, in 2009/2010, the variation of surface flow velocity was smaller and showed an elevation-dependence along a longitudinal section;along a transverse section the maximum surface flow velocity was close to the main flow line and gradually decreasing to the both sides. All flow direction was parallel to the main flow line, directing the glacier terminal. In the surveyed area, it is found that the surface flow velocities of the southeast edge were faster than those of the northwestern edge. As compared with other glaciers which have similar glacierized area, the flow velocity of the Ningchan River Glacier No. 3 is faster.
  • ZHAO Jing-dong, WANG Jie, SHEN Yong-ping, YIN Xiu-feng, WU Yun-fei
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 841-847. https://doi.org/10.7522/j.issn.1000-0240.2013.0095
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    The northwest of the Die shan, as the western segment of the Qinling Mountains, is located in the eastern margin of the Qinghai-Xizang Plateau. Glacial erosional and depositional landforms, including cirques, U-shaped valleys, hanging valleys, palaeo-firn basins, whaleback rocks, polished bedrocks, and lateral and end moraines are well preserved in this mountainous area above 3 700 m a.s.l. Remote-sensing techniques and field mapping were applied to study the distribution and features of glacial landforms in this area. Based on the distribution and features of glacial landforms, considering the present uplift speed of the Qinghai-Xizang Plateau, the available dating data of the glacial landforms in the Dalijia Mountain and the data of the palaeoenvironment in the neighboring areas, the glacial landforms are considered to be formed in the last glacial cycle, especially during the Last Glacial Maximum. The ancient glacier was an ice cap with a maximum area of about 38 km2. Abundant whaleback rocks that present at about 4 200 m a.s.l. indicate that the ancient ice cap had a warm bottom.
  • LIU Xiao-qin, WU Qi-hua, LI Hong-qin, MAO Shao-juan, LI Ying-nian
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 848-856. https://doi.org/10.7522/j.issn.1000-0240.2013.0096
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    Exclusion is one of the most promoted measures in grassland restoration. At present, it is necessary to study the vegetation-soil carbon density of alpine meadow with different enclosures. Based on monitoring 1-year, 6-year and 16-year grazing exclusion plots, it is found that: 1) the existing vegetation carbon density of alpine meadow with different enclosure durations is in the order of 16-year grazing exclusion plot (1 522.57 gC·m-2) > 1-year grazing exclusion plot (1 323.12 gC·m-2) > 6-year grazing exclusion plot (1 148.17 gC·m-2), with a density variation statistically insignificant (P>0.05);2) the soil carbon density has a significant vertical distribution, with relatively high organic carbon density at 0~5 cm and 5~10 cm depths, soil organic carbon density greatly reducing downwards and soil bulk density increasing with depth. Moreover, the differences in soil organic contents and in soil bulk density are not statistically significant (P>0.05) between different enclosure ages, but the soil carbon density at 0 40 cm depth has the order of 1-year grazing exclusion plot (28 636.32 gC·m-2) > 6-year grazing exclusion plot (26 570.92 gC·m-2)> 16-year grazing exclusion plot (26 060.71 gC·m-2). The soil bulk density reduces with enclosure age;3) by monitoring the net ecosystem CO2 exchange (NEE) from lately July to early October, it is found that the soil carbon uptake rate of 1-year grazing exclusion plot is significantly higher than that of 16-year grazing exclusion plot (P<0.05), but their release rates are almost the same, with a difference statistically insignificant (P>0.05).
  • LIU Hong-Lan, ZHANG Qiang, HU Wen-chao, GUO Jun-qin
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 857-864. https://doi.org/10.7522/j.issn.1000-0240.2013.0097
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    Using the precipitation data from 121 representative observation stations in Northwest China from 1961 to 2011, the characteristics of spring precipitation were analyzed. EOF, REOF and power spectrum method were used to research the spatial and temporal characteristics of spring precipitation in Northwest China. Whether there were mutations in the spring precipitation sequence was tested by Mann-Kendall test. The results show that the spatial distribution of spring precipitation in Northwest China was extremely uneven. One can see that the rainy areas located in the southeast and northwest, and the less rain areas located in the middle. Spring precipitation was consistent in the entire region at the first space scale, two natural climate zones could be recognized with the second space scale, and six natural climate zones could be recognized with the third space scale. The 1980s was the most precipitation decade among the five decades. The 1970s was least precipitation decade. The annual variability of spring precipitation was significant in Northwest China. Precipitation in most precipitation year was three times more than that in least precipitation year. There were obvious mutations in spring precipitation in Northwest China from 1961 to 2011. An abrupt decreasing occurred in 1973, and an abrupt increasing occurred in 1985. As regards of changing cycles, there was a long period of 18 19 years (the main) and short periods of 5 years and 7 years. It is expectancy that spring precipitation in Northwest China would be slowly coming down in the future 20 years.
  • WANG Su-ping, ZHANG Cun-jie, SONG Lian-chun, LI Yao-hui, FENG Jian-ying, WANG Jin-song
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 865-873. https://doi.org/10.7522/j.issn.1000-0240.2013.0098
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    Based on the correlation analysis between soil relative humidity and meteorological drought indexes in 5 areas of China, the impact of meteorological drought on the soil moisture is discussed. The results show that due to the differences in water and thermal conditions, the time scale of meteorological drought which causes soil drought is different in different seasons and different areas. In spring, the amount of precipitation since last year, especially in late autumn and early winter, has obviously impact on the soil relative humidity in Northeast China, while in the eastern part of Northwest China, North China, Southwest China, Huanghuai, Jianghuai and Jianghan areas, the soil relative humidity is closely depended on the atmospheric moisture in recent two months. In summer, soil relative humidity in the five areas is closely related to precipitation and temperature in recent two months. In autumn, the meteorological drought in recent two to four months will control the soil drought in the northern part of China and in other four areas;the soil relative humidity is strongly correlated with atmospheric moisture in recent two months. In addition, a soil relative humidity prediction model through multiple linear regressions based on the main indexes is developed with the data from 1992 to 2007 in each area in spring, summer and autumn. The efficiency of each model is also verified with data from 2008 to 2011. The results show that these models have certain ability to fit the soil relative humidity with the mean absolution deviation within 10.1% to 13.9%, (11.7% in average). Among them, the deviation in the east of Northwest China and North China is larger in spring and summer, with the fitting accuracy of drought classes between 65% and 74.9%. In Northeast China, Southwest China, Huanghuai, Jianghuai and Jianghan areas, the model is more effective, with a fitting accuracy above 88%. The fitting curves of soil relative humidity on May 28th, Aug. 28th, Sept. 28th, 2011 also verify the feasibility of these models.
  • DAN Dan, CHUN Xi, LIU Mei-ping, LIU Yue
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 874-882. https://doi.org/10.7522/j.issn.1000-0240.2013.0099
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    Based on monthly mean air temperature and monthly precipitation data from nine meteorological stations in Huolin River basin from 1951 to 2010, using climatic linear trend, Mann-Kendall test and correlation analysis methods, the spatial-temporal characteristics of climatic change in this region were analyzed in this paper. The results indicated that the annual temperature had increased 2.3 ℃, with an increasing rate of 0.38 ℃·(10a)-1 showing an up ward trendin general from 1951 to 2010 in the basin.The increase of temperature in spring was most obvious,with a changing rate of 0.50 ℃ ·(10a)-1.The annual mean temperature had an abrupt change mainly in 1986,and the temperature averaged from 1987 to 2010 was more than 1.3 ℃ higher than that from 1951 to 1986.There were significant cyclical changes with 6~8 and 15 aperiod. Annual precipitation had fallen 83.9 mm,with a decreasing rate of 13.98 mm·(10a)-1 and a downward trend in general from 1951 to 2010.The decrease of precipitation was most pronounced in summer,with adecrea singrate of 11.41 mm·(10a)-1.Annual precipitation abrupt was mainly observed in 1998, and the precipitation averaged from 1998 to 2010 was 76 mm less than that from 1951 to 1997. There were significant cyclical changes with 4 years and 8~9 years periods. It is found that the change in temperature has positive correlation with AO index and the change in precipitation negatively correlates with EAP index.

  • SONG Gui-ying, LI Xiao-ze, SUN Yong-gang, CHEN Lei, JIANG Jing, XUN Xue-yi
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 883-891. https://doi.org/10.7522/j.issn.1000-0240.2013.0100
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    In late July 2012, an extreme heavy rainstorm swept the inland arid and semiarid zones in the central area of Inner Mongolia, China, which was a new problem for meteorology and climatology, especially for weather forecast. In Hetao region the heavy rainstorm event occurred on 20 July. The daily precipitation records in two stations exceeded historical extreme. In another station the record exceeded historical threshold. In this paper, the causes of the event are analyzed with NCEP reanalysis data, conventional observations and monitoring. It is found that: 1) the cold air from Lake Baikal invaded into the warm air of the subtropical high. Vortex system was inspired in the lower troposphere. The water vapor taking by south wind along the front of vortex system reached to north of 41°N and gathered in Hetao. The water vapor flowed from lower troposphere to the mid-level with a flux of 8~10 g·cm-1·hpa-1·s-1 and an atmospheric specific humidity up to 12~17 g·kg-1, which provided abundant moisture to the extreme storm;2) the extreme rainstorm was due to the strong development of the MCC. A meso-scale convective system MCS developed in northwest Hetao. A β meso-scale convective system from south incorporated it. A MCC was developed with its TBB value of -40 ℃ to -83 ℃ at the centre. There were β meso-scale convective echo groups in northeast and central Hetao, within which the echo of each convective cell reached 50-55 dbz, forming super convective cells. The continuously growing ground convergence lines triggered convective rainstorms in northeast Hetao;3) before the rainstorm, high unstable energy accumulated owing to the lower troposphere warming. Dry intrusion increased atmospheric instability further. Then, Hetao extreme rainstorm occurred, when the atmospheric instability energy was released owing to strong upward movement of the front warm air;4) the event was closely related to global warming. Along with global warming, the ice volume in high latitude and Arctic is decreasing, causing the cold vortex activity decreasing, while summer monsoon is increasing, causing the rain belt moving northwards. Therefore,it is not occasional that extreme rainstorm occurs in the middle latitude semiarid inland.
  • ZAN Mei, LI Deng-qiu, JU Wei-min, WANG Xi-qun, CHEN Shu-jiang
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 892-903. https://doi.org/10.7522/j.issn.1000-0240.2013.0101
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    The ability of HJ-CCD remote sensing data to retrieve vegetation leaf area index (LAI) and its sensitivity to atmospheric correction methods were investigated in the Kanas National Nature Reserve, Xinjiang. The 6S and FLAASH models were employed to implement atmospheric corrections for the remote sensing data. The changes in the reflectance and vegetation indices (NDVI, SR, SAVI, MSR, ARVI) of different land cover types (needle leaved forests, broad leaved forests, mixed forests, and grasslands) with and without atmospheric correction were analyzed. Then, the best fitted models for estimating LAI were built with the field measurements of LAI and spatial distribution patterns of LAI were analyzed. The results show that after atmospheric correction, the reflectance in the visible bands decrease. Reflectance in the near infrared band increases with the atmospheric correction by the 6S model and decreases with the atmospheric correction implemented by the FLAASH model. Consequently, atmospheric correction causes NDVI, SR, MSR and SAVI (except needle leaved forests) to increase. As to ARVI, the influence of atmospheric correction is related to the correction model used and vegetation types. With the atmospheric correction by the 6S model, ARVI decreases for all land cover types. The atmospheric correction conducted by the FLAASH model causes ARVI to increase for need leaved and broad leaved forests and to decrease for mixed forests and grasslands. Atmospheric correction enhances the linkage between LAI and vegetation indices. The models based on reflectance with the atmospheric correction by the 6S model are better than the models base on reflectance with atmospheric correction by the FLAASH model for forests (needle leaved forests, broad leaved forests, and mixed forests). As to retrieval of LAI for grasslands, the model based on reflectance with the atmospheric correction by the FLAASH model outperforms the model based on reflectance with the atmospheric correction by the 6S. The results indicate that the HJ-CCD data can be used to estimate LAI in the study area with atmospheric correction properly implemented. In the locations near lakes and rivers, LAI of vegetation is high. Low LAI is distributed at locations with high elevation. The LAI averages of mountain forest-steppe zone, subalpine forest zone, alpine shrub meadow, alpine tundra and alpine glaciers are 2.6, 3.9, 2.5, 1.7 and 1.0, respectively.
  • GAO Juan, FENG Mei-mei, GAO Qian
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 904-912. https://doi.org/10.7522/j.issn.1000-0240.2013.0102
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    As the development of city metro, artificial freezing method is widely used in connected aisle construction. For ensuring the safety of projects, to get appropriate freezing parameters and guidelines and to find out the excavation influence on stability of stratums are very important. Considered phase change and frost heave deformation, based on the thermal-hydrological-mechanical (THM) coupling theories, the freezing and excavation processes of a certain connected aisle in metro was simulated by COMSOL finite-element analysis software. The transformations of seepage field, temperature field and displacement field during freezing period and the deformation of stratums after excavation were analyzed. It is found that owing to the seepage of water, the distribution of temperature field and seepage field are no longer symmetrical about y-axis, and the thickness of the frozen wall in the upstream is less than that in the downstream. During the process of freezing, the transformation of frost heave deformation shows linear increase firstly, and then becoming steady. The maximum frost heave deformation of surface appears at the right side of y-axis. Overall, artificial freezing of stratum is helpful for increasing the intensity and stability of solid, and also possesses a well effect on water isolation and deformation controlling.
  • GENG Ke
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 913-919. https://doi.org/10.7522/j.issn.1000-0240.2013.0103
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    For understanding comprehensively the influences of freeze-thaw cycle and frost heaving force on the structures of tunnel in the cold regions, taking the highway tunnel in cold region in Inner Mongolia (Alatan Highway Tunnel) as an example, the frost heaving forces were calculated by the method of elasticity mechanics in this paper. The thermal-stress field coupling analysis on the tunnel section was done with the finite element simulation software-ANSYS. The frost heaving pressures on the tunnel section after freeze-thaw cycles of 50 years are worked out. The results with the elastic mechanics method and on-situ test are compared and analyzed. It is found that the theoretical and the numerical simulated results are relatively similar. The change in loading condition on the structures during the tunnel operation can be understood by comparing the theoretical and numerical simulated results of frost heaving pressures on the tunnel. Thus the degree of safety and reliability of the tunnel structures can be determined.
  • LAN Yong-chao, LU Cheng-yang, LA Cheng-fang, SHEN Yong-ping, JIN Hui-jun, SONG Jie, WEN Jun, LIU Jin-peng
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 920-928. https://doi.org/10.7522/j.issn.1000-0240.2013.0104
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    The changing characteristics and trends of regional climate in the source regions of the Yellow River and the response of runoff to climate change are analyzed based on the observational data of air temperature, precipitation and runoff at some hydrologic stations and precipitation stations, as well as some weather stations. The results show that after a strong climate shift from warm-dry to warm-humid in the west of Northwest China, such as Xinjiang and western Hexi Corridor of Gansu in the late 1980s, a similar climate change has occurred since the mid-2000s in the source regions of the Yellow River, which is located in the east of Northwest China. The background is global warming, and the climate change leads to precipitation and runoff increasing in the regions. The new observational data of precipitation and runoff in the regions display that the average annual precipitation in the source regions of the Yellow River has exceeded the long-time average value in most years since 2004, and then the runoffs through all hydrologic sections on the main stream of the Yellow River have also increased incessantly, exceeding the long-term average, since 2008. However, it is difficult to determine the prospects of climate change. It is necessary to do further research and observation on the rate and extent of the climate change in time and space in the regions. It is very possible that the climate shift from warm-dry to warm-humid in the source regions of the Yellow River in the decadal time scale, which is expected from the analysis and forecast of the activity of the East Asian monsoon and from the observed stream runoff change.
  • WEN Jing, WANG Yi-bo, GAO Ze-yong, LIU Guo-hua
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 929-937. https://doi.org/10.7522/j.issn.1000-0240.2013.0105
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    The research is carried out in Beiluhe River basin on the Tibetan Plateau, which is in the source regions of the Yangtze River, where degrading meadows are severely affected by the freezing and thawing, with the methods of choosing typical areas and quadrats to do experiment and simulation, and then studying the soil water characteristics, soil saturated hydraulic conductivities, soil particle size fractionation, soil bulk density and other soil porosities at different depths. The results show that the power function equation proposed by Gardner et al. and van Genuchten has a good simulation function to the soil moisture characteristics;there is a critical value of the soil moisture, 0.1 MPa. It is found that the water-retention capacity of the soil at the depth of 0~5 cm is the minimum, and that at the depth of 20~30 cm is the maximum. It is indicated that the soil at the depth of 0~5 cm has the poorest capacity of water supplying. The soil at the depth of 15~30 cm shows the greatest water supplying capacity, which is the optimum soil layer for the growth and development of plant roots. It is also found that the soil saturated hydraulic conductivity decreases with depth.
  • REN Yu-long, SHI Yan-jun, WANG Jin-song, LI Yi-ping, ZHU Yong-jun, YANG Zi-he, WEI Bo-long
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 938-948. https://doi.org/10.7522/j.issn.1000-0240.2013.0106
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    In this paper, monthly precipitation data from 137 meteorological stations in Northwest China from 1961 to 2009 were used to calculate the standardized precipitation index (SPI). Then the frequencies and area ratios of the light drought, severe drought and extra severe drought, monthly and in the four drought durations (late spring, early summer, summer and autumn), were calculated. Their spatial and temporal characteristics were also analyzed. The results show that (1) northern Xinjiang region, central Qinghai and Hexi Corridor of Gansu are the regions with highest drought frequencies, more than 15 months. While in southern Xinjiang region the drought frequency is lower, except for individual months;locations of the drought area has an moveforward trend from south to north, from west to east with months;(2) the severe drought frequencies of the most parts of Northeast China are less than 5 months, expect for individual areas in Xinjiang, Qinghai and Gansu. The frequency in southern Xinjiang region is still lower. The frequency in summer is higher than that in the other seasons. Northern Xinjiang region and Hexi Corridor of Gansu are places with extra severe drought;(3) drought area ratios of different grades has the similar annual changing characteristics, which generally can be divided into three periods: high drought frequency period (the average drought rate was about 35%) from 1961 to 1980, transition period (the drought rate was about 15%) from 1981 to 1990 and stabilization period (the drought rate less changed, with a slight increasing in recent years) from 1991 to 2009;(4) global warming leads to increase precipitation and glacier meltwater, streamflow and lake water level, causing drought area rate declining since 1987.
  • YANG Jian-ling, FENG Jian-min, MU Jian-hua, ZHENG Guang-fen, TAN Zhi-qiang, WANG Su-yan
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 949-958. https://doi.org/10.7522/j.issn.1000-0240.2013.0107
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    Drought, the most serious meteorological disaster, can induce serious problems such as agricultural production reduction, water shortage, land desertification, ecological environment degradation and so on. At the beginning of a new round of the national implementation of the western development strategy, under the background of global warming, it is necessary to analyze the new characteristics and variation trend of drought in detail for providing scientific decision-making and reference of strengthening prevention and fight against drought, in order to further promote economic development. Based on the daily air temperature and precipitation data from 74 meteorological observation stations in the east of Northwest China, adopting the national standard comprehensive drought index (CI index), application of which has been promoted to all over the country in recent years, the temporal and spatial distribution and variation trend of different levels of drought days in different seasons in the east of Northwest China are analyzed in detail. It is found that under the background of global warming, the long-term trend of drought is aggravating in spring, summer and autumn, but is lightening in winter in the east of Northwest China. Since the beginning of the 21st century, the spring and summer droughts have aggravated, especially in summer, while the autumn and winter droughts have lightened. The severe/extreme severe drought from March to November has intensified more significantly than light/medium drought, and the drought trend in south part has intensified more than that in the north part. Furthermore, it is found that the spring drought has aggravated significantly in Tongxin of Ningxia, where a most serious area of severe/extreme severe drought in the east of Northwest China is forming. To this new trend of drought development, it is necessary to pay great attention for the related departments, and to adopt scientific and effective methods to strengthen preventing and fighting against the drought.
  • ZHAO Xuan, LI Yao-hui, QI Dong-mei
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 959-967. https://doi.org/10.7522/j.issn.1000-0240.2013.0108
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    Based on the precipitation data of 119 stations from 1961 to 2010, the temporal and spatial variations of summer precipitation in Sichuan were analyzed by using the EOF, REOF linear trend, Mann-Kendall analysis and Morlet wavelet analysis. The analyzed results are as follows: The summer precipitation presents a downward tendency during the 47 years. Abrupt changes appeared in 1962, 1982 and 2000, respectively. There were changing periods of 22 and 6-8 years. Spatially, the summer precipitation in Sichuan can be subdivided into the following four regions: east Sichuan basin, mid-west Sichuan basin, southwest Sichuan mountain region and western Sichuan plateau. Summer precipitation was increasing in east Sichuan basin and western Sichuan plateau, was decreasing in mid-west Sichuan basin and more stationary, perhaps with a little increasing, in southwest Sichuan mountain region. In the four regions, there were unique annual and decadal variations in summer precipitation, with changing periods of 23, 16, 14, 12, 8 and 6 years.

  • LI Yi-ping, WANG Jin-song, LI Yao-hui
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 968-977. https://doi.org/10.7522/j.issn.1000-0240.2013.0109
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    Two methods for identifying monthly drought process are contrastively analyzed by using daily CI index of 160 stations in the Yellow River basin during 1961-2008. The results show that generally speaking, both methods can identify severe drought events in the basin in monthly time scale, but the identified intensity and range are not the same. Spatially, the first method can identify the severe drought events in a large scale;the whole identified drought area includes or even sometimes exceeds the real drought area. While, the second method can roughly identify the drought area, and usually miss some small part;As regards the drought intensity, the first method may identify the severe drought under weight, while the second way may identify the drought more consistent with the actual situation. In the middle-west part of in the Yellow River, we can draft a line of southwest-northeast direction for the boundary, the Yellow River basin is divided into two parts, the west of the boundary is including the regions of the northwestern Qinghai, middle-western Gansu, western Inner Mongolia, the east of the boundary is including the regions of the southeastern Qinghai, southeastern Gansu, eastern Inner Mongolia, Ningxia, Shaanxi, Shanxi, Henan and Shandong provinces. According to monthly drought frequency analysis, for the west regions of boundary of the Yellow River basin, there are less drought events, while for the east regions of boundary of the Yellow River basin, there are different results. According to the first method identifying, monthly drought frequency is larger in the west regions of boundary of the Yellow River basin, with frequent light drought and low frequency of extreme severe drought. According to the second method identifying, monthly drought frequency is not so large in the east regions of boundary of the Yellow River basin, about 60%~80%.The second method is recommended to use. By this method, severe drought frequency is the first, followed by medium drought.
  • CAI Xiao-jun, MAO Hai-xiang, WANG Wen
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 978-989. https://doi.org/10.7522/j.issn.1000-0240.2013.0110
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    It has significant practical importance to study drought indices, which are the basis for research of arid climate. The Z-index, precipitation anomaly percentage, relative humidity index, standardized precipitation index, and CI index were calculated by using the data of daily precipitation, daily averaged temperature and relative humidity from 1960 to 2010 at 34 meteorological observation stations over the Yangtse-Huaihe River basins. Compared with drought records, it is found that Z-index is the best one among the five drought indexes for describing the drought events with the coincidence rate up to 70%. Temporally, Z-index is good normally, except in April-June, with a match rate of more than 70%. SPI index is as good as Z-index, except in January-February. MI index is the poorest among the five drought indices. CI index is most suitable in Henan Province, but is poor in Shandong Province. It seems better in summer than in spring and autumn. Seasonally, CI is most suitable in summer, followed by Z-index and SPI. In autumn and winter Z-index is rather good, followed by SPI and Pa. In spring, SPI and Pa are good.
  • SHA Sha, GUO Ni, LI Yao-hui, REN Yu-long, LI Yi-ping
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 990-998. https://doi.org/10.7522/j.issn.1000-0240.2013.0111
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    The relationships between satellite-based vegetation condition index (VCI) and a number of frequently used meteorological drought indices, including meteorological drought composite index (CI), K drought index (K), the percentage of precipitation anomalies (Pa), standard precipitation index (SPI), Z-index (Z), Palmer drought severity index (PDSI) were evaluated by using long-term monthly data in Henan Province from 1982 to 2006 in this paper. The temporal lags between VCI and meteorological indices and the capabilities of using VCI to monitor drought is also discussed. The results show that: 1) Underlying surface has an impact on the correlations between VCI and meteorological indices. The correlation of VCI with meteorological drought indices of cropland is higher than that of woodland. There is a positive correlation between VCI and meteorological drought indices on cropland. 2) There are differences in the temporal lags during different growing stage of crops. During over-winter stage of winter wheat, the lag is one to three months. During summer corn stage, it is one month. The affection of meteorological condition to summer corn is inferior than that to winter wheat. Overall, combining with prophase meteorological condition, VCI is able to indicate meteorological drought and to monitor drought in the province.
  • HAN Hui, LI Yao-hui
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 999-1006. https://doi.org/10.7522/j.issn.1000-0240.2013.0112
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    Based on the ground climatic data from 62 meteorological stations in Gansu Province from 1960 to 2005, the changing trends of meteorological element extreme (MEE) during crop growth period (from March to October) were analyzed, and the impacts of MEE on agro-meteorological disasters were discussed with principal component analysis. The results showed that those MEEs related to temperature have statistically significant trends just same as average air temperature;those MEEs related to precipitation have non-significant trends but show the precipitation structure in Gansu Province changing to less extremeness. The results also showed that the maximum wind speed descends significantly, the evaporation anomaly has a non-significant descending trend and the sunshine duration anomaly has a non-significant ascending trend. Results of the principal component analysis indicated that most of MEE changes are corresponding with the changes of agro-meteorological disasters and only a few of them are of reverse phase. Comprehensive analysis of the variations of the MEEs in Gansu Province reveals that drought disaster will exacerbate and flood disaster will decrease in the future.
  • WANG Wen, LI Wei, LI Yao-hui
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 1007-1014. https://doi.org/10.7522/j.issn.1000-0240.2013.0113
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    Using the daily NCEP/NCAR reanalysis dataset and the observation rainfall data in the middle and lower reaches of the Yellow River from 1971 to 2010, the characteristics of low-frequency oscillation (LFO) during drought/flood years over the middle and lower reaches of the Yellow River are analyzed. The results show that LFO of 10~20 d and 30~60 d universal exist in the middle and lower reaches of the Yellow River in drought and flood years, of which LFO of 30~60 d presents the characteristics of regional distribution, with large value in the middle and lower reaches. LFO of 10~20 d shows the integrity distribution. LFO of 10~20 d is stronger than that of LFO of 30~60 d in the whole. LFO of 30~60 d is more notable in flood years than in drought years. LFO of 30~60 d propagation characteristics in flood years is not the same as in drought years. Meanwhile the LFO of 30~60 d propagation characteristics in flood years are also different. There are two causes to impact the low frequency precipitation in the flood years. One is the LFO intensity strengthening in low-latitude and spreading northward to the Yellow River basin;another is the LFO of heat sources in the Tibet Plateau eastward spreading and intersecting with the LFO of heat sources westward spreading from West Pacific at the middle and lower reaches of the Yellow River. In the normal year low-frequency precipitation is mainly affected by the impact of the low-latitude LFO northward spreading, when LFO in low-latitude northward spreading intersects with the LFO westward spreading from West Pacific over the middle and lower reaches of the Yellow River.
  • NA Li, ZHENG Guang-fen, REN Shao-yun, XU Jian-qiu
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 1015-1021. https://doi.org/10.7522/j.issn.1000-0240.2013.0114
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    Based on the precipitation data from meteorological stations in Ningxia from 1961 to 2010, the spring, summer and fall precipitation-concentration period (PCP), precipitation-concentration degree (PCD) and the Z-index are calculated, and their spatio-temporal variations are further studied by using trend analysis, correlation analysis and synthesis analysis. It is found that during the 50 years, the drought grade was increasing in spring, summer and fall, especially in fall. The drought in the central arid area was most serious, followed by the southern mountainous area, and was lightest in the northern area. There was no significant change in PCP during spring and fall, but a slight decrease in summer. The PCD went up and down, respectively, in spring and summer, without obvious change in fall. During the last 10 years, the PCD had grown significantly in all the three seasons, while the PCP had been postponed in spring and summer. However, the drought grade was distinctly affected by the time of first soaking rainfall instead of PCD in spring. Early soaking rainfall often led to low drought grade, and vice versa. In summer, the PCD had a greater influence on the drought grade than on PCP. The highly concentrated rainfall will increase the possibility of flood, while the drought will appear more often when PCD is low. The drought grade is affected by both PCP and PCD in fall. High PCD and early PCP imply more floods, otherwise more drought.
  • DUAN Hai-xia, WANG Jin-song, LIU Yun-yun, LI Yi-ping, WANG Su-ping
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 1022-1035. https://doi.org/10.7522/j.issn.1000-0240.2013.0115
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    In order to study the features and causes of the drought disasters, the drought events and their atmospheric circulation anomalies in Southwest China from autumn, 2009 to spring, 2010 was examined by using observed daily precipitation data, daily East Asia monsoon index, daily subtropical high index, 74 atmospheric circulation indices and NCEP/NCAR reanalysis data. The results show that: 1) The continuous stronger East Asia monsoon and western Pacific subtropical high by west by north led to Southwest China controlled by western Pacific subtropical high and higher air temperature due to East Asia monsoon established from the end of October, 2009. A stronger cold air controlled northern China, precipitation occurred mainly in the North China and East China, so less cold air and warm air intersected over Southwest China and drought disaster occurred and developed. 2) The India-Burma trough was weaker than mormal, so moisture from the Indian Ocean and the Bay of Bengal was not enough. Both water vapor fluxes from the Bay of Bengal and from the South China Sea were under the normal. The Southwest China was located in a sinking motion anomaly region since autumn of 2009, causing continuous drought. 3) In September, 2009, an El Niño event took place, triggering atmospheric circulation anomalies, which resulted in an anomalous anticyclonic flow field in the South China Sea and the western Pacific. The anticyclonic flow field shifted to west and south of normal position, so the western Pacific subtropical high position shifted to west and south of normal position. At the same time, cold air was difficult to move southwards, affecting the Southwest China;the India monsoon was decline, the warm moist air flows from the Indian Ocean decreased with less vapor, so the rainfall in Indian monsoon regions of the Yunnan-Guizhou Plateau and its surrounding was less. 4) The OLR anomalies on the Tibetan Plateau and the South China Sea, near the Philippines, and the intertropical convergence zone had a close relationship with the western Pacific subtropical high and precipitation in Southwest China.
  • YUAN Shu-jie, WANG Ting, WANG Peng
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 1036-1043. https://doi.org/10.7522/j.issn.1000-0240.2013.0116
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    Water shortage in different growth stages is the first factor for paddy climate drought. By the data of daily precipitation, daily mean air temperature in different paddy growth stages from 159 weather stations in Sichuan Province from 1960 to 2010, the probability of different climate drought level are analyzed in the paddy tillering stage, jointing booting stage and heading and flowering stage by using the precipitation anomaly percentage and the relative moisture index as a drought index. Paddy climate drought disaster risk modes are constructed, then the climate drought risks are assessed in the paddy tillering stage, jointing booting stage, heading and flowering stage and the whole growth period in the province. The results show that: there are higher climate drought risks in paddy jointing booting stage and heading and flowering stage in the province;spatially, there is some difference between the risk zonings from precipitation anomaly percentage and from relative humidity index, but the risk distribution trends are similar. The higher risk areas are mainly in Sichuan Basin and northeastern part of Sichuan Province, and the risk in the south is smaller in the whole paddy growth stage.
  • WU Zhe-hong, ZHAN Pei-gang, CHEN Zhen-hong, BAI Hui, WANG Jin-song
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 1044-1055. https://doi.org/10.7522/j.issn.1000-0240.2013.0117
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    In this paper, the meteorological drought indexes CI and K were used to analyze the spatial and temporal distribution, evolution characteristics and abrupt changing of meteorological drought from 1971-2011 in Anshun Municipality of Guizhou Province. It is found that for severe drought process, the two indexes are all able to recognize;for the drought process the recognized results are consistent with real process over the years;the CI is more accurate and the K has better continuity. The seasonal drought analysis found some consistent conclusions. For example, the drought probability is smaller in summer, and the average drought length of all seasons are basically the same. The linear evolution trend analysis and the M-K test results found that the summer drought intensity was decreasing, spring and autumn drought intensity was increasing, annual drought length was also increasing. These consistent findings are considered of high credibility. From the M-K curves the above changing trends are detected. From the M-K curves the whether abrupt changing are also detected. Annual drought length has increased since 2008. Summer drought intensity has mitigated and autumn drought intensity has increased since the end of last century. The length of the spring drought has increased since the mid-1970s. Autumn drought length increased from the mid-1980s to the 1990s, followed by a mutation. According to the Mexican hat wavelet analysis, it is believed that there are a changing period of 12~13 years for the annual drought intensity and a period of 4~6 years for the annual drought length.
  • Alimujiang Kasimu, TANG Bing, Gulikezi Tulake
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2013, 35(4): 1056-1064. https://doi.org/10.7522/j.issn.1000-0240.2013.0118
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    Using multi-temporal satellite remote sensing data and GIS technology, urban spatial information was extracted. Using of urban expansion intensity, urban growth rate and compactness and fractal dimension index of the urban spatial form, the processes and features of Xinjiang urban spatial-temporal dynamic changes during 1990-2010 was analyzed. The following main conclusions can be drawn: 1) The cities of Xinjiang have the dependence on unique natural environment and oasis economy, which decide the spatial distribution of cities. Development of many cities depends on oasis, characterized by a hydrophilic. Due to vast territory, urban zones or urban agglomerations are relatively concentrated near the traffic trunk. 2) There are obvious differences in the propagation speed and strength between South and North Xinjiang. In North Xinjiang, the cities in the economic zone on the northern slopes of the Tianshan Mountains have more fast expansion speed and more high expansion intensity, while in South Xinjiang the cities have slower expansion speed and low expansion intensity. 3) Analysis of the changes in compactness and fractal dimension of Xinjiang cities finds that average compactness is decreasing, while the fractal dimension is increasing, which indicate that the spatial structure of cities is loosing and the urban spatial structure is unreasonable. It is necessary to be improved.