On the Relationship between Local Topography and Small Glacier Change under Climatic Warming on Mt. Bogda, Eastern Tian Shan, China

Glacial features in the geological record provide essential clues about past behavior of climate. Of the numerous physical systems on earth, glaciers are one of most responsive to climate change, especially small glaciers, their direct marginal response taking only a few years or decades to be expressed. Accelerating recession of modern glaciers raises the issue of the climate’s impact on water runoff. Data based on topographic maps and Advanced Spaceborne Thermal Emission and Radiometer (ASTER) imagery sho...     

地形地貌条件对兰州市泥石流灾害形成影响分析

通过对兰州市地质灾害详细调查确定的各类泥石流灾害点148处的统计,统计分析了地形地貌主要表现在沟床比降、沟坡坡度、流域面积、相对高差、流域形态和沟壑密度对泥石流控制影响分析,并对泥石流有主要控制影响的沟床比降、沟坡坡度、流域面积、相对高差4项进行了相关性分析,对该区域泥石流灾害的预警预报有一定的指导意义。     

Eigen solutions of internal waves over subcritical topography

Diapycnal mixing plays an important role in the ocean circulation.Internal waves are a kind of bridge relating the diapycnal mixing to external sources of mechanical energy.Difficulty in obtaining eigen solutions of internal waves over curved topography is a limitation for further theoretical study on the generation problem and scattering process.In this study,a kind of transform method is put forward to derive the eigen solutions of internal waves over subcritical topography in twodimensional and linear framework.The transform converts the curved topography in physical space to flat bottom in transform space while the governing equation of internal waves is still hyperbolic if proper transform function is selected.Thus,one can obtain eigen solutions of internal waves in the transform space.Several examples of transform functions,which convert the linear slope,the convex slope,and the concave slope to flat bottom,and the corresponding eigen solutions are illustrated.A method,using a polynomial to approximate the transform function and least squares method to estimate the undetermined coefficients in the polynomial,is introduced to calculate the approximate expression of the transform function for the given subcritical topography.     

Fine-scale population structure in a deep-sea teleost (orange roughy, Hoplostethus atlanticus)

Microsatellite and otolith chemistry variability were analysed to assess fine scale genetic structure in the deep-sea teleost orange roughy (Hoplostethus atlanticus). The Porcupine Bank located on the continental shelf west of Ireland, comprises a complex system of mounds and flat areas that are broken up by canyons. Orange roughy form spawning aggregations on mounds and flat areas, and were heavily fished until the resource was depleted. By analysing adults in spawning condition and juvenile orange roughy from six mounds and one flat area, shallow but significant genetic population structure was evident (F_ST=0.0031, D_est across loci=0.0306 and G-test). Most of the structure was accounted for by inclusion of a sample from the flats (six of ten significant pairwise F_ST estimates and G-tests, and five of the highest D_est estimates included the flat sample). While the flat sample contributed most to the genetic structure, there was still significant (albeit weaker) structure among mound samples. The observed structure was supported by otolith analyses. Fish caught as late juveniles in either the flat or mound areas showed consistent differences in chemistry at the otolith core throughout the initial 10 years of growth, which could indicate site fidelity. We hypothesise that seafloor topographic structures (mounds and flats) may provide discrete spawning areas for orange roughy and that the limited gene flow between these spawning areas is insufficient to counteract genetic drift.     

EFFECTS OF THE ENVELOPE DEGREE OF OROGRAPHY ON THE SIMULATED CLIMATE PROPERTIES*

A primitive equation model with a zonal domain and a p-σ incorporated vertical coordinate system is used to study the effects of the envelope degree of orography on the simulated properties of both winter and summer climates.Results show that the orography with a larger envelope degree can improve the simulations to certain extent,especially in winter.It is found that the simulated properties of climate are mainly determined by the co-effects of the land-sea and the orographic distributions,and the envelope degree of orography has a secondary effect.However it should be taken properly in order to improve simulations:otherwise,it would be harmful.Different envelope degrees of orography can be adopted in different areas.     

Land surface in gravity points classification by a complete system of curvatures

A general theory of land surface in a gravitational field is being developed. The four classes of topographic variables are defined: local (class A) and global (class B) that have no sense without gravity, and local (class C) and global (class D) which are gravity invariant. A complete system of curvatures is introduced for a general situation of nonuniform gravity. The curvatures refer to classes A and C, the latter being subject of the differential geometry of surfaces, the former being subject of this work in a special section of mathematics concerned with surfaces in a vector field. The svstem of curvatures consists of 7 known ones of the classes A and C and 5 new curvatures of the class A (difference, horizontal excess, vertical excess, total ring, and total accumulation curvatures). Seven new theorems show in which way curvatures can reflect landforms and their ability to influence substance flows, and the relationship between them. Land surface in gravity-points classification is constructed based on signs of curvatures, which includes known curvature-based classifications as partial situations, and 12 main types (from total 48) are shown to form open subsets of the surface with equal probability to meet them for the land surface as indicated by a new statistical hypothesis. A central-point method for local variables calculation in uniform gravity approximation is described for a computer Digital Elevation Models treatment.     

论震波频谱图- 地震波的三维显示

震波频谱图，又名“震波凸形图（Seismic topography)“是S.J.Duda关于谱震级概念的发展，对应于宽频带地震图盯应于每一道带通频率fm来折算的瞬时振幅所组成的面（为二维包络面），沿着时间轴作出剖面，例如，0．3赫芝的带中频率相匹配的带通滤波器所输出的包络线，而三维可视化技术则允许快速估算其相庆振幅的分布，要能判明其高峰位置的相应分布，则不太容易，因此我们就将其剖面投影在二维的分布图上，为了辨识震波强度的分布，将此图配上相应的颜色，及其前置的颜色标尺，与其振幅值相对应，图中的等值有助于识别图中的峰和谷并与高或低强度相对应，这种对宽频记录时间－频率分布的表方式，用颜色和等值线来表示振幅值，我们称它为“频谱震波图”。可转化为三维图形，其中每一条线代表由相应带中频率fim计算得的包络线，用灰度表示等值线，可转化为三维图形，其中每一条线代表由相应带中频率fm计算得的包络线，用灰度表示等值线，估算震波强度或振幅的二维分布，又称为“震波凸形图”，它反映了在地震台记录的信号能量随频率和时间的分布，从而看出其最大强度所对应的频率范围，震波叔谱图允许对随时间而变化的频谱分量在时间和强度的定位方面有较好的分辨率，在中国及邻近地区已试用该方法，说明有助于识别地震系列的特征。     

应用GIS制作《陕西省气候资源及专题气候区划图集》

通过《陕西省气候资源及专题气候区划图集》的编制，针对小网络资料推算和专题气候区划空间叠置分析所遇到的问题，提出实现分区域小网格推算和根据区划模型评判打分的叠置分析的技术方法，该方法的应用为利用GIS制作陕西省气候资源数字图像和专题气候区划数字图像，奠定了基础。     

大布苏湖东岸“狼牙棒”地形成因探讨

经野外实地勘查研究,并采取土样进行易溶盐、孢粉分析,结合地貌形态特征与化验成果进行研究论证,认为“狼牙棒”地形的形成与其特殊的岩性条件和内、外动力地质作用相关,对“狼牙棒”地形形成机理进行探讨。     

Variations in geometric measures of topographic surfaces underlain by fractured granitic plutons

Silicate melts impose systematic fracture patterns on their hosts and their own subsolidus portions as they crystallize and cool to ambient conditions. Weathering of these plutonic bodies accentuates the fractures and produces fragmented topographic surfaces whose geometric measures exceed those of a Euclidean surface. Because geometric measures of these surfaces are potentially indicative of the percolation properties of the fracture network, contours and vertical sections were digitized from 1250000 and 1240000 scale maps, and their statistical fractal dimensions,D, were computed. Regions underlain by granitic plutons with similar fragmentation patterns were found to haveD values ranging from 1.15 to 1.28 within a single pluton. This range of values is caused by noise and several geologic factors. The values contain noise introduced by the map-making and digitizing procedures that amounts toD1.05. However all values lie well above this threshold, and they correlate closely with local differences in weathering. SmallerD values derive from contours where accumulation of screen or glacial erosion has smoothed the surface, whereas largerD values derive from contours along aretes and in unglaciated terrains. In each of these regions, largerD values occur locally where fractures are most frequent and/or continuous. LargeD values were also derived from regions underlain by host rocks that lie in the near-field region of the stress field caused by the pluton. The fractral values derived are apparently related to the magma-hydrothermal event, they can potentially be used to derive properties of the percolation networks that were active during the hydrothermal events.