A synthetic Earth for use in geodesy

 A synthetic Earth and its gravity field that can be represented at different resolutions for testing and comparing existing and new methods used for global gravity-field determination are created. Both the boundary and boundary values of the gravity potential can be generated. The approach chosen also allows observables to be generated at aircraft flight height or at satellite altitude. The generation of the synthetic Earth shape (SES) and gravity-field quantities is based upon spherical harmonic expansions of the isostatically compensated equivalent rock topography and the EGM96 global geopotential model. Spherical harmonic models are developed for both the synthetic Earth topography (SET) and the synthetic Earth potential (SEP) up to degree and order 2160 corresponding to a 5′×5′ resolution. Various sets of SET, SES and SEP with boundary geometry and boundary values at different resolutions can be generated using low-pass filters applied to the expansions. The representation is achieved in point sets based upon refined triangulation of a octahedral geometry projected onto the chosen reference ellipsoid. The filter cut-offs relate to the sampling pattern in order to avoid aliasing effects. Examples of the SET and its gravity field are shown for a resolution with a Nyquist sampling rate of 8.27 degrees. Received: 6 August 1999 / Accepted: 26 April 2000     

陨石氧同位素组成及其地学意义

介绍了各类陨石氧同位素组成的特点,对陨石氧同位素组成的主要成因观点进行了评述,结合地球的原始物质组成,讨论了陨石氧同位素组成的地球科学意义。     

研究人为地质作用是当代地学发展的必然趋势

本文根据地球科学的最新研究进展,探讨了人类活动所引发的各种地质作用－人为地质作用的性质、特点和规律,以及全球变化和人类社会发展的影响。人类对地球的依赖与破坏而产生相互失调的矛盾,始终是解决人类社会与地球关系中一个最突出的问题。因此,加强对人为地质作用的研究不仅有助于这一问题的解决,而且拓宽了地质学的研究领域和服务范围,对促进地球科学的发展将起着重要的作用。     

新生代构造抬升对地表化学风化和全球气候变化的影响

全球新生代构造抬升 ,特别是南亚喜马拉雅青藏高原和南美安底斯山脉和Altiplano高原在新生代的抬升对地表化学风化和全球气候变化产生了重要影响。它对地表化学风化的影响主要表现为引起造山带地区化学风化能力的提高 ;而它对全球气候变化的影响则主要表现在两个方面 ,一是直接的物理影响 ,即通过对大气和海洋循环的影响来对大气变化产生作用 ;一是通过对地表硅酸盐岩石的化学风化造成大气CO2 变化和全球温度的改变 ,从而对气候变化产生间接的生物化学效应。目前看来 ,新生代构造抬升造成的大气CO2 浓度减少是造成全球新生代气候变冷的重要原因。这已得到了近 10年来计算机大气环流模型 (GCMs)数值模拟和野外实验研究的支持 ,但在关于地表化学风化的主要控制因素 ,以及海洋Sr同位素是否可作为反映地表化学风化速率变化的替代性标志和气候变化反馈机制等方面 ,还需要作进一步研究。     

Digital earth, Virtual Reality and urban seismic disaster simulation

1 IntroductionIn January 1998 US Vice President AJ Gore proposed his revoluhonny concept of Digital ~. ms visionof a mulh-resoluhoft three~ensional representation of our planet has stimulated many geo-scientists topursue new wads of managing our planet. As for many prachCal aPPlications. eve need to stUdy the Earth'ssurface, interior and the Earth's processes in three dimensions. The technology of Virtual Reality, where wecombine GIS, remote sensing bogery, and other data sources, is b…     

Microscale Response of Sediment Variables to Benthic Disturbance in the Central Indian Ocean Basin

The response of sediment bacteria and biochemical variables to benthic disturbance was investigated in the Central Indian Ocean Basin from cores at nine stations. Generally, bacterial density and biochemical variables declined vertically with depth in the upper layers of the cores. Mechanical disturbance caused by a hydraulic disturber brought about a substantial decrease in total bacterial numbers. However, the numbers of retrievable bacteria increased by two orders of magnitude. The biochemical parameters decreased in quantity with a shift in the linear relationship. The data suggest that abiotic artifacts will directly affect the biomass and biochemistry of the sediment.     

近地小行星轨道演化的研究

本文主要阐述了近年来我们在近地小行星轨道演化研究所获得的一些基本结果,即合理的力学模型和相应的有效算法,并以实际预报算例与有关权威性的结果作了比较,证实这些研究结果确实是可信的。     

Secular changes of LOD associated with a growth of the inner core

From recent estimates of the age of the inner core based on the theory of thermal evolution of the core, we estimate that nowadays the growth of the inner core may perhaps contribute to the observed overall secular increase of LOD caused mainly by tidal friction (i.e., 1.72 ms per century) by a relative decrease of 2 to 7 µs per century. Another, albeit much less plausible, hypothesis is that crystallization of the inner core does not produce any change of LOD, but makes the inner core rotate differentially with respect to the outer core and mantle. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

论新世纪衡阳城市形象的定位与塑造

衡阳市以位处南岳衡山之南而得名,自古以来自然、人文景观并胜,社会、经济、文化发达.近20多年来各方面反而停滞和落后.文中运用企业识别CI原理,从城市形象发展历史和现状入手,将其新世纪城市总体形象定位为"江南内陆腹地重要现代化区城中心 ,湘南最大交通枢纽,全国著名的山水旅游城市,环境优美、安全舒适的人居休闲胜地". 并指出城市形象塑造应体现古城衡阳的气韵和文脉,给人以古老文明、开拓进取、不断创新的总体视觉形象,以推动新世纪衡阳城市的总体发展.     

合成孔径雷达( SAR)及其在地质和地震研究中的应用

在遥感技术广泛应用的今天, 合成孔径雷达( SAR)因其具有全天时、全天候成像能力及对地物有一定穿透力等独特的特点, 已成为地学研究的一个重要手段。概述了合成孔径雷达技术的发展状况, 对合成孔径雷达成像机理及特征做了简要介绍, 同时对新兴起的合成孔径雷达干涉测量( IN SAR)技术也做了简单描述, 并就SAR在地质和地震研究中的应用进行了举例说明, 充分肯定了合成孔径雷达技术在地质和地震研究中的重要作用。