Phases Representing Source Lengths of Tsunami in Tide Gauge Records

We identified a phase representing the source length of tsunami's in the tide gauge records around Japan. This phase was observed at tide stations, located in the direction of the long axis of the sources, for four large tsunamis: 1964 Niigata, 1968 Tokachi-oki, 1983 Nihonkaichubu, and 1993 Hokkaido-nanseioki. The phase consists of two continuous crests starting as the initial arrival and has a time length of 15–47 minutes. This is the time required to propagate across the source area along the long axis. Strong evidence that the phase is generated at the source is the good correlation between waveform observed at one side and time-inversed waveform at another side. The correlation results from the instantaneous generation of the source. The source lengths of 74–254 km were obtained under an assumption of sea depths at the sources and verified to coincide with ones within a relative error of 15% that were previously obtained by other methods.     

关于实孔径雷达影像匹配定位问题

地面高程起伏对机载雷达成像定位影响较大,要实现飞行器的精确定位,必须修正地形起伏的影响。分析了雷达成像的几何关系及特点,分别从影像匹配定位和飞行器定位两方面探讨了地形起伏的影响,对地形起伏影响的修正方法进行了研究,提出了适于飞行器上实时处理的误差修正算法,并利用该方法对实验中获取的数据进行了改正,得到了满意的结果。     

东北地区高精度GPS定位试验初步结果

1990年8月至9月间,武汉测绘科技大学和黑龙江省测绘局合作,圆满完成了国家高精度GPS空间定位网的东北地区一个环的GPS测量试验工作。该项试验取得了预期的效果。表明了国家高精度GPS空间定位网初步设计的技术目标的可行性,并为该网的组织实施和作业调度提供了经检。通过试验,为发展完善了观测技术方案和外业数据检检方法,及全网的布测实施提供了必要的依据。     

中国东南陆缘大地水准面的确定

利用我国东南地区１１８２２个重力数据、３０″×３０″数值地形模型和ＷＤＭ９４重力位模型,以Ｓｔｏｋｅｓ理论为基础,采用低通滤波方法处理远区影响,计算了中国东南陆缘２．５′×２．５′格网重力大地水准面,其结果与福建、山东的ＧＰＳ水准相比较,精度分别为±０．１２４ｍ和±０．０６２ｍ。     

高程现代化问题

海拔高在工程应用中有不可代替的作用。测量海拔高的经典方法是几何水准,它的主要缺点是劳动强度大、效率低、花费大、实时性差。GPS海拔高测量在很大程度上克服了这些缺点,而且可以满足许多应用的高程需求。GPS海拔高测量代替水准测量,以GPS海拔高测量为主的\"高程现代化\"代表大地测量的一个发展方向。     

球面小波分析技术及在全球重力模型中的应用

在介绍球面小波理论的基础上,推导和比较了几种球面小波,分析了最新地球重力模型——EGM96,以此为依据,把球面小波多分辨分析用于计算全球自由空气异常及重力大地水准面,并对处理结果做出解释。     

卫星测高研究应用新进展

卫星测高是利用空间技术进行海洋观测的崭新技术手段。GEOSAT卫星的升空又使得这一研究向前大大地推进。本文简要介绍卫星测高在确定大地水准面精度、研究岩石圈特性、探测海底深部构造、研究海洋动力环境以及其经济效益和社会效益的最新进展。     

地球重力位模型确定局部大地水准面起伏的比较研究

分析了EGM2008、EGM96、GGM02等几种地球重力位模型的阶方差,为得到各模型中长波分量和短波分量的精度,利用研究区域内GPS水准数据分别对所选模型120阶和360阶计算得到的大地水准面高进行了比较,又考虑到地形和实测重力数据缺失对大地水准面的影响,把研究区域划分为平原和山地丘陵两部分,并比较了两个地区内参考点上模型计算值的精度,利用最小二乘原理对模型计算值进行了拟合改正。     

利用北斗GEO卫星观测数据探测中尺度电离层行波扰动

根据GEO卫星的特点,给出了电离层扰动序列的提取方法以及扰动振幅、周期的获取方法,并根据实测的2012-04-16～２０１２－０４－１８的观测数据,对探测到的电离层扰动进行了初步分析。实验结果显示,1号GEO卫星在2014-04-17T12:30左右探测到扰动,5号GEO卫星和4号GEO卫星分别在2012-04-17T18:50～２０１２－０４－１７Ｔ２０:45和2012-14-18T06:00～２０１２－０４－１８Ｔ０７:23探测到扰动,探测的电离层扰动发生时间及扰动的振幅、周期等传播特性与前人研究基本一致,而且提取的扰动序列不包含多谱勒效应的影响。     

Detection of major geological structures in the Eastern offshore of India using Geosat altimeter data

Satellite altimetry can be used to infer subsurface geological structures analogous to gravity anomaly maps generated through ship-borne survey. The Eastern offshore was taken up for analysis using Geosat Exact Repeat Mission (ERM) altimeter data. A methodology is developed to use altimeter data as an aid to offshore hydrocarbon exploration. Processing of altimeter data involves corrections for various atmospheric and oceanographic effects, stacking and averaging of repeat passes, cross-over correction, removal of deeper earth and bathymetric effects, spectral analysis and conversion into free-air gravity anomaly. The final processed results were derived for Eastern offshore in the form of prospecting geoid and gravity anomaly maps and their spectral components. The highs and lows observed in those maps were derived in terms of a number of prominent megastructures e.g., gravity linears, 85°E and 90°E ridges, the Andaman trench complex etc. Satellite-derived gravity profiles along 12°N latitude match well with the existing structures.