地球系统科学与数字地球

数字地球将为地球系统科学研究带来研究方法,研究手段和信息获取渠道的革命,因对地观测和数据资源共享技术的发展将使传统的野外地学作业逐步走向现代化,从而使地球系统科学的建立真正成为可能。     

海岸带与地球系统科学研究

从系统的定义出发, 本文简要回顾了提出地球系统科学的背景与过程。地球系统科学研究已经成为地学领域的研究焦点与热点,并带动和加速了地球信息机理、陆地地球系统科学和全球变化的研究。本文重点分析海岸带在地球系统中所处的特殊位置,海岸带研究在地球系统科学研究中起着重要作用。简要介绍海岸带科学前沿-海岸带海陆交互作用计划 （LOICZ）.     

数字地球视角下的城市规划及展望

基于文献分析方法,综合分析了数字地球的概念,总结了数字地球技术在城市规划中的应用.其主要包括:数据源扩展技术;定量分析技术;公众参与支持系统;动态监测系统;基于云计算模型与时态GIS的城市规划时空展示分析体系;城市规划教育与创新体系.认为凭借其多分辨率、三维动态可视化以及海量数据存储的特点,数字地球技术在城市规划中的应用将具有广阔的发展前景.     

Limitations of Waveform Modelling of Long-Period Seismograms

In recent years the use of synthetic seismograms calculated for radially stratified models has gained increasing popularity as a means of placing further constraints on the velocity structure of the Earth's mantle. Such synthetics do. however, have a number of limitations. At short periods (∼1 s) the amplitudes as well as the wave shapes of travel-time branches are affected by seismograph siting, the structure immediately beneath the seismograph and any laterally heterogeneous structure in the mantle. Later arrivals can also be masked by signal-generated noise and by extended source times. At longer periods (∼-20 s) the larger wavelengths reduce the sensitivity of amplitudes and waveforms to contaminating effects. As a result the use of long-period synthetics can only lead to the resolution of the gross features of the Earth's interior.     

Extraterrestrial coastal geomorphology

Earth is the only planet in the solar system where large amounts of liquid water have been stable at the surface throughout geologic time. This unique trait has resulted in the production of characteristic landforms and massive accumulations of aqueous sediments, as well as enabled the evolution of advanced and diverse forms of life. But while Earth is the only planet with large bodies of water on its surface today, Venus and Mars may have once had lakes or oceans as well. More exotic fluids may be stable in the outer solar system. Prior to the Voyager flybys of the outer planets during the 1970s and 1980s, the moon of Neptune, Triton, was thought to be much larger than the Voyager cameras revealed it to be, and predictions that liquid nitrogen lakes or oceans might be found were made. The moon of Saturn, Titan, however, was found to have a massive atmosphere, so the possibility remains that it may have, or may once have had, lakes or oceans of liquid hydrocarbons. The recent, high-resolution synthetic aperture radar imaging of Venus has failed to reveal any evidence of any putative clement period, but the results for Mars are much more intriguing. Herein, we briefly review work on this subject by a number of investigators, and discuss problems of identifying and recognizing martian landforms as lacustrine or marine. In addition, we present additional examples of possible martian coastal landforms. The former presence of lakes or oceans on Mars has profound implications with regard to the climate history of that planet.     

云南北部山原红壤成土年龄的初步研究

根据红壤成土过程中的元素迁移模型，本文初步求解了云南北部山原红壤成土过程中的硅迁移强度值（Px），并对不同海拔高程上的山原红壤发育年龄进行了计算。     

“数字地球”的启示

本文分析了“数字地球”这一全球战略思想带给我们的一些启示 ,这些启示包括 :战略眼光 ,大国地位 ,自主发展和技术引进 ,盲目追随、整合的意义等。笔者认为 ,宏观的、全局性的战略眼光 ,冷静思考与明确的目标 ,紧抓对地观测和国家基础信息设施建设以维护中国作为大国的形象和利益 ,在发展“数字中国”过程中走自主发展与技术引进相结合的道路 ,以及加强行政管理机制、智能化数据、科研机构和学科领域的整合 ,是我们在数字地球的挑战面前应有的基本思路。     

Image resolution and evaluation of genetic hypotheses for planetary landscapes

The spatial resolution of image data tends to constrain the horizontal length scale of genetic hypotheses that are addressable by those data. No ‘simple’ formula exists when image resolution is sufficient to test a given geomorphic process, which is dependent on what characteristics are diagnostic of the particular process. Genetic hypotheses should be formulated along the lines of the “multiple working hypotheses” concept as described in a classic paper by Chamberlin [J. Geol. 5 (1897) 837]. An essential element of a viable working hypothesis is a clear indication of the characteristics predicted by, or a consequence of, the hypothesis. An untestable hypothesis is not an effective working hypothesis. The history of the study of lunar sinuous rilles is outlined as an illustration of the influence of image resolution and the formulation of genetic hypotheses on the subsequent advancement of understanding of the problem. Sinuous rilles on Venus and Mars, and controversial sinuous ridges on Mars are also reviewed. In the lunar case, the three-order-of-magnitude improvement in spatial resolution provided by Lunar Orbiter photographs over Earth-based telescopic photographs did not result in definitive examination and elimination of published hypotheses for the formation of sinuous rilles. Topographic data obtained from cartographically controlled Apollo orbital photographs, along with important observations and samples obtained by the astronauts on the lunar surface, did test and exclude several hypotheses. The formulation of a genetic hypothesis, including testable consequences of that hypothesis, is a greater determinant of its ultimate utility to the scientific community than is the image resolution available at any given time.     

The application of geodetic radio interferometric surveying to the monitoring of sea-level

Summary. Under project IRIS (International Radio Interferometric Surveying) geodesists are using Very Long Baseline Interferometry (VLBI) to monitor polar motion to 1-2 ms of arc and UT1 to 0.05-0.10 ms, and to develop a global geodynamic network to detect and study centimetre level displacements of reference points associated with large-scale phenomena such as tectonic plate motion and glacial rebound. Differential positioning techniques using the signals broadcast by the satellites of the Global Positioning System (GPS) are being used to study finer scale phenomena, such as localized subsidence, and economically to relate these specialized surveys to the geodynamic network. Including tide gauge stations in this system will make it possible to detect motions of specific gauges and correct or delete the measurements from those gauges when computing changes in sea-level. The National Oceanic and Atmospheric Administration (NOAA) has selected several tide gauges on the east and west coasts of the United States, and initial epoch GPS surveys to tie the gauges to VLBI observations have already begun. Other countries participating in project IRIS are planning similar activities. In addition to providing a globally based land reference datum for the tide gauge measurements, the IRIS polar motion and UT1 time series may contribute directly to monitoring and interpreting global sea level changes. Changes in the volume and distribution of ice masses result in long-term motions of the axis of rotation, and sea-level changes affect the length of day (lod). The IRIS time series will certainly have the resolution required to detect the expected polar motion and changes in lod, and a properly designed global VLBI/GPS network should allow the ice/sea-level effects to be separated from crustal dynamics effects.     

Using Digital Earth to Expose Students to GIScience

Students in U.S. geography programs face particular challenges that may discourage them from taking advanced GIScience courses and considering geospatial careers. This article provides a preliminary discussion of the development, delivery, and evaluation of a University of Colorado Colorado Springs sophomore-level, required geography course designed to address this concern. The course, Digital Earth (DE), introduces students to the principles, concepts, and applications of major geographic information technologies (GITs) early in their academic careers. The success of DE is evaluated by examining the extent to which the course excited students about GIScience and motivated them to take higher level elective geospatial courses. Results suggest that DE generates considerable student interest in GIScience, prepares students reasonably well for elective courses, and greatly inspires them to seek a geospatial career.