不同数学模型在降水量资料序列订正中适用性探讨

采用逐步多元线性回归模型、一元线性回归模型、综合法模型和比值法模型对分布于全国31个台站的降水量资料进行了模型订正效果的试验与分析。结果表明:（1）逐步多元线性回归模型对年降水量序列的订正效果较好,其相对拟合误差总平均在0.08以下,而其它3种模型与月降水量序列的订正效果较差,相对拟合误差总平均在0.11以上;（2）若将年降水量序列相对拟合误差控制在0.10以内,则要求确定订正方程式的平行资料年数为10年或以上,要求订正站与基本站序列的相关系数在0.85以上;（3）较湿润地区拟合误差较小,反之较大。     

A comparison of drainage networks derived from digital elevation models at two scales

Automated generation of drainage networks has become increasingly popular with powerful analytical functions in geographic information systems (GIS) and with the increased availability of digital elevation models (DEMs). This paper compares drainage networks derived from DEMs at two scales, 1:250 000 (250K) and 1:24 000 (24K), using various drainage parameters common in hydrology and geomorphology. The comparison of parameters derived from the 250K DEMs with those from the 24K DEMs in 20 basins ranging from 150 to 1000 km² in West Virginia shows that the goodness-of-fit between parameter estimates based on the DEMs varies. Results clearly show that superior estimations are produced from the 24K DEMs. Better estimates can be obtained from the 250K DEMs for stream length and frequency parameters than for gradient parameters. However, the estimation of the mean gradient parameters based on the 250K DEMs seems to improve with increasing terrain complexity. Finally, basin size does not strongly affect the accuracy of parameter estimates based on the 250K DEMs.     

起算震级与衰减不确定性校正

分析表明,起算震级Ｍ０对危险性分析结果的表现为当Ｍ０取取值不够低时,场地的危险性将被低估。此种低估影响与场地的地震危险性高低潜源距场地的距离及衰减公式的形式和标准差有关。     

Landslide zoning in a part of the Garhwal Himalayas

 The Himalayas are undergoing constant rupturing in the thrust belt zone in the Garhwal Himalayas, due to which earthquake and mass movement activity is triggered. These processes of mass movement and landslides have been constantly modifying the landscape. Landslides are one of the indicators of the geomorphological modifications taking place in this active and fragile terrain. This work is aimed at providing another example of landslide susceptibility mapping based on geological and geomorphological attributes. The data collected from aerial photographs, topographic sheets and the image suggests that there is a correlation between the distribution of landslides and some of the geological and geomorphological factors, for example, the distance from an active fault, relative relief and slope. Parameters like factor of safety, altitude, relief, slope and the distance from the fault lineament have been included in the study. A rating system has been applied to the factors for arriving at a quantitative estimate of landslide susceptibility for each physiographic unit. Since terrain classification forms the foundation of this work, the entire study can be grouped into two sequential activities: (1) the terrain classification and (2) landslide susceptibility mapping. The result is the landslide susceptibility zoning map presented. The landslides have not been classified with respect to time and may represent the final result of the on-going geological, geomorphological and seismic activity since the Holocene period or late Pleistocene time when the glaciers retreated. The area chosen for the study lies between Badri gad and Barni gad in Yamuna valley region of the Garhwal Himalaya where a very large scale investment is in the pipe line for Hydroelectric power generation. Received: 12 August 1993 · Accepted: 13 January 1998     

TOVS 水汽反演的误差分析及其订正

该文利用同步物理反演法以6小时数值预报场为背景场对1992年1月份NOAA-12卫星垂直探测（TOVS）资料进行了大气参数反演，并对水汽反演误差进行了检验和分析。以常规观测作为检验的标准，检验结果按3条轨道统计，发现反演的相对湿度平均误差与背景场的误差密切相关，均为负值；在高层和高纬度，误差绝对值随高度的增加而增加，随纬度的升高而增加；误差的日际变化在高层比较稳定，低层振动较大。对反演误差进行订正后的结果表明，在500 hPa以上反演均比背景质量要好，尤其轨道A所有层次上订正后的反演比背景场好。     

数字摄影测量系统生成的DEM数据精度的确定

论述一个由数字化画幅式像片（或数字影像）用数字摄影测量系统生成的DEM数据精度的确定方法。该方法的特点是只使用数字摄影测量系统的观测,避免了其它测量系统（如解析测图仪）的影响。通过在数字视频测图仪（DVP）上所作的大量实验证明本文中设计的方法是普遍实用的。实验结果表明,影响DEM数据的精度的主要因素是像元大小。     

利用共线方程对空间实验室影象进行数字几何纠正

本文论述了利用共线方程对空间实验室影象实施数字几何纠正的理论依据、数据准备、外方位元素解求过程中参量的确定及锚点纠正法的可行性和纠正精度,提出了纠正过程中几个必须注意的环节,以提高精度,缩短机时。同时还介绍了自编软件包的组成。     

GZCORS在广州市某测区地形测量中的应用

本文介绍了广州市连续运行参与站系统(GZCORS)和广州市似大地水准面精化成果确立的广州市城市三维定位系统在地形图测量中的应用,并通过实例分析其精度。     

格莱尼改正及其在地球物理数据处理中的意义

格莱尼改正是重力改正的一种,是对球面半径约166.7 km以外地形和均衡造成的重力综合效应的改正,改正后所得格莱尼异常可对应研究区范围内地壳结构特征,具有重要的研究意义.但近年来国内的重力研究中,对格莱尼改正的认识和重要性还不是十分透彻,特别是在大区域研究中,忽略这一远区重力效应可能会对研究结果的解释造成误导.针对这一问题,本文介绍了格莱尼改正的含义、由来与研究历史,指出了在大区域研究中需要考虑格莱尼效应的重要性,以“扇形球壳块”法为例给出了格莱尼改正的计算原理,列举了格莱尼异常在地球物理中的常见应用,并通过重力改正与莫霍面深度反演实例,通过对反演结果的控制点检测与精度评价,指出格莱尼异常反演所得莫霍面埋深更接近地震方法结果,从而表明了格莱尼改正在地球物理研究中的不可忽视性,并指出完全布格改正与格莱尼改正在计算方法上可实现统一.