青藏高原局地因素对近地表层地温的影响

青藏高原近地表层地温既受区域性因素（高度、经度、纬度）控制，同时又受局地因素的影响。观测结果表明，高原稀疏植被地段比裸地地温高，短时期薄层雪盖起降低地温的作用，南坡比北坡地温高2－7℃，黑色沥青路面年平均温度比碎石土天然的年平均地表温度高4．5℃，亦高于其它材料的路面地温。     

青藏高原东南缘玉龙雪山（5596m）晚新生代隆升的侵蚀与构造控制作用

玉龙雪山位于青藏高原东南缘,它以其独特的地貌特征而引人关注。其顶部为一古残留面,在30×20km²范围内海拔>5000m的山峰达18座,高出其周围地区平均海拔近1000m。在分析该区地质地貌特征基础上,我们根据岩石圈弹性挠曲地壳均衡理论,以较保守的残留面海拔4250m为当时金沙江下切玉龙雪山的基准面,结果表明:由于虎跳峡中大规模物质剥蚀而引起玉龙雪山地壳均衡反弹,导致山体隆升了468m,这完全是侵蚀作用对于玉龙雪山隆升的贡献。而玉龙雪山与周围地区的剩余地势高差,主要由正断层等构造作用造成。因此,玉龙雪山的隆升是侵蚀与构造作用共同控制的结果。该区最大量地壳均衡反弹的触发机制是5.0².5M a期间玉龙雪山东西两侧正断层的发生。另一方面,作为玉龙雪山的南东延伸部分——点苍山（4122m）在5.0².5M a同样也发生了构造伸展,但是没有遭受大规模的河流侵蚀作用,因此其海拔相对要低很多。这进一步说明地壳均衡反弹导致了玉龙雪山隆升,并加大了玉龙雪山与点苍山在原有基础上的地势高差。     

Evaluation of the SNOWPACK model’s metamorphism and microstructure in Canada: a case study

The snow thermodynamic multi-layer model SNOWPACK was developed to address the risk of avalanches by simulating the vertical properties of snow. Risk and stability assessments are based on the simulation of the vertical variability of snow microstructure, as well as on snow cohesion parameters. Previous research has shown systematic error in grain size simulations (equivalent optical grain size) over several areas in northern Canada. To quantify the simulated errors in snow grain size and uncertainties in stability, the snow specific surface area (SSA) was measured with a laser-based instrument. Optical grain size was retrieved to validate the optical equivalent grain radius from SNOWPACK. The two study plots are located in Glacier National Park, BC, and Jasper National Park, AB, Canada. Profiles for density and stratigraphic analysis were obtained as well as grain size profiles, combined with snow micropenetrometer (SMP) measurements. Density analysis showed good agreement with the simulated values (R² = 0.76). Optical grain size analysis showed systematic overestimation of the modeled values, in agreement with the current literature. The error in SSA evolution for a rounding environment was mostly constant, whereas error for conditions driven by a temperature gradient was linked to the size of the facetted grains.     

Wintertime Seasonal Scale Simulation over Western Himalaya Using RegCM3

The Himalayan region of north India is composed of complex mountain ranges with different altitudes and orientations, causing prevailing weather conditions to be complex. Wintertime eastward moving synoptic weather systems `Western Disturbances' (WDs) yield large amounts of precipitation over this region. Numerous micro/mesoscale circulations become generated along with prevailing weather due to surface heterogeneity and land-use variability of the Himalayan region. WDs along with these circulations may give rise to very adverse weather conditions over the region. Intraseasonal variability of surface climate over the Himalayas is studied using regional climate model (RegCM3) with 60 km resolution. A 6-month (Oct. 1999–Mar. 2000) period, as this period has received an enormous amount of precipitation in the form of snow, is considered to study surface climate variability in terms of temperature, precipitation and snow amount. Model simulations show cold bias over the Himalayan region and warm bias over the northwest India. Average monthly distribution of temperature indicates that a controlled experiment could capture the areas of lowest temperature regime. Precipitation fields could be simulated only up to a certain degree of satisfaction and the influence of topographic elevation and valleys needs to be seen. RegCM3 provides a representation of resolvable atmospheric circulations that results in explaining mean variability during winter.     

II: Wind related errors in different methods of solid precipitation measurement

Using data sets assembled within the WMO Solid Precipitation Measurement Intercomparison, the paper deals with the wind related losses in national methods of solid precipitation measurement. Fourteen different types of precipitation gauges are included in the Harzgerode/GDR intercomparison field. Initial results of the comparisons between the Valdai double fence reference method and the other gauges in terms of dependence on wind speed and type of precipitation are presented. These results reveal that the national unsheltered HELLMANN gauge catches only 24 per cent to 70 per cent of the daily totals of solid precipitation as compared with the reference gauge. Results of the analysis of monthly totals and individual events reveal a similar dependence of gauge deficiencies on wind speed and type of precipitation. Case studies of single snow falls and the wind field conditions around and within the double fence reference are also described.     

利用MODIS资料对积雪的遥感监测

通过对遥感卫星资料中云和雪的光谱特征的分析，提出利用中分辨率成像光谱仪（MODIS）红外、可见光谱段数据进行云、雪检测和分离的方法；并提供监测实例来说明利用MODIS数据可进行积雪监测。     

欧亚和青藏高原冬春季积雪与我国夏季降水关系的分析和预测应用

通过高原积雪和欧亚积雪与我国夏季降水的相关分析和统计检验,表明冬春季雪盖对我国夏季旱涝有重要的影响,虽然冬季和春季雪盖与我国夏季降水的相关分布存在差异,总趋势大致相仿。但是,冬春季高原积雪和欧 亚积雪与我国夏季降水的相关分布基本是相反的,其中高原积雪与长江中下游和西北东部地区夏季降水为正相关,欧亚积雪与东北和华北东部以及西南地区降水为正相关冬季节积雪异常偏多时,长江流域夏季易发生洪涝,这也是汛期降     

基于TM和ETM~+数据的玛纳斯河流域积雪时空分布特征研究

为了进一步研究玛纳斯河流域积雪的时空分布特征以及影响因素,应用遥感技术,以Landsat TM(美国地球资源探测卫星系统上加载的专题绘图资料)以及ETM+(增强型专题绘图资料)为数据源,利用雪盖指数法对研究区进行了积雪信息提取。通过对提取积雪信息的研究,分析了研究区的积雪时空分布的特征,并详细分析了高程、坡度、坡向以及其他因素对于积雪分布的影响。结果表明研究区积雪空间分布随高度和地形变化非常明显,积雪主要分布高海拔地区,而山间河谷地带则相对较少,同时积雪受季节影响较大,主要集中在秋、冬、春3个季节;并得出高程、坡向对积雪分布影响比较大,而坡度对积雪分布影响则相对较小的规律特征。     

The variability of the snow and ice melt in alpine rivers in northwestern China

The study of snow and ice melt （SIM） is important in water-scarce arid regions for the assessment of water supply and quality. These studies involve unique difficulties, especially in the calibration of hydro-models because there is no direct way to continuously measure the SIM at hydrostations. The recursive digital filter （RDF） and the isotopic hydro-geochemical method （IHM） were coupled to separate the SIM from eight observed series of alpine streamflows in northwestern China. Validation of the calibrated methods suggested a good capture of the SIM characteristics with fair accuracy in both space and time. Applications of the coupled methods in the upper reaches of the Hei River Basin （HRB） suggested a double peak curve of the SIM fraction to streamflow for the multi-component recharged （MCR） rivers, while a single peak curve was suggested for the rainfall-dominant recharged （RDR） rivers. Given inter-annual statistics of the separation, both types of the alpine rivers have experienced an obvious decrease of SIM since 196os. In the past 10 years, the SIM in the two types of rivers has risen to the levels of the 1970s, but has remained lower than the level of the 1960s. The study provided a considerable evidence to quantify the alpine SIMbased on the separation of observed data series at gauge stations. Application of the coupled method could be helpful in the calibration and validation of SIM-related hydro-models in alpine regions.     

The influence of seasonal snow on soil thermal and water dynamics under different vegetation covers in a permafrost region

Seasonal snow is one of the most important influences on the development and distribution of permafrost and the hydrothermal regime in surface soil. Alpine meadow, which constitutes the main land type in permafrost regions of the Qinghai-Tibet Plateau, was selected to study the influence of seasonal snow on the temperature and moisture in active soil layers under different vegetation coverage. Monitoring sites for soil moisture and temperature were constructed to observe the hydrothermal processes in active soil layers under different vegetation cover with seasonal snow cover variation for three years from 2010 to 2012. Differences in soil temperature and moisture in areas of diverse vegetation coverage with varying levels of snow cover were analyzed using active soil layer water and temperature indices. The results indicated that snow cover greatly influenced the hydrothermal dynamics of the active soil layer in alpine meadows. In the snow manipulation experiment with a snow depth greater than 15 cm, the snow cover postponed both the freeze-fall and thawrise onset times of soil temperature and moisture in alpine LC （lower vegetation coverage） meadows and of soil moisture in alpine HC （higher vegetation coverage） meadows; however, the opposite response occurred for soil temperatures of alpine HC meadows,where the entire melting period was extended by advancing the thaw-rise and delaying the freeze-fall onset time of the soil temperature. Snow cover resulted in a decreased amplitude and rate of variation in soil temperature, for both alpine HC meadows and alpine LC meadows, whereas the distinct influence of snow cover on the amplitude and rate of soil moisture variation occurred at different soil layers with different vegetation coverages. Snow cover increased the soil moisture of alpine grasslands during thawing periods. The results confirmed that the annual hydrothermal dynamics of active layers in permafrost were subject to the synergistic actions of both snow cover and vegetation coverage.