Measuring magnetic field in the 'diamagnetic' ionosphere

Satellite magnetometers sometimes pass through regions of plasma, such as the terrestrial ionosphere, where the ionization is large enough that some of the original ambient field is excluded from the plasma. This reduction of field inside the plasma region comes from the 'diamagnetic' effect of the charged particles in their helical trajectory around the magnetic field lines. The (container of the) magnetometer will exclude the plasma, and a simple-minded approach, treating the ionosphere in the same way as for a conventional diamagnetic fluid, predicts that the field seen by the magnetometer will be somewhat larger than the (reduced) field in the plasma. However, the 'diamagnetic' properties of the ionosphere are quite different from those of a conventional diamagnetic. In particular, there is a 'reflection' of the ionospheric charged particles at the surface of the magnetometer, and the overall effect is that the magnetometer does actually measure the field present in the plasma before the magnetometer is inserted. Similarly, any leakage fields from the magnetometer have no effect in the magnetosphere.     

Improved magnetic anomalies of the Antarctic lithosphere from satellite and near-surface data

The Antarctic magnetic anomaly map compiled marine and airborne surveys collected south of 60°S through 1999 and used Magsat data to help fill in the regional gaps between the surveys. Ørsted and CHAMP satellite magnetic observations with greatly improved measurement accuracies and temporal and spatial coverage of the Antarctic, have now supplanted the Magsat data. We combined the new satellite observations with the near-surface survey data for an improved magnetic anomaly map of the Antarctic lithosphere. Specifically, we separated the crustal from the core and external field components in the satellite data using crustal thickness variations estimated from the terrain and the satellite-derived free-air gravity observations. Regional gaps in the near-surface surveys were then filled with predictions from crustal magnetization models that jointly satisfied the near-surface and satellite crustal anomalies. Comparisons in some of the regional gaps that also considered newly acquired aeromagnetic data demonstrated the enhanced anomaly estimation capabilities of the predictions over those from conventional minimum curvature and spherical harmonic geomagnetic field models. We also noted that the growing number of regional and world magnetic survey compilations involve coverage gaps where these procedures can contribute effective near-surface crustal anomaly estimates.     

Coseismic and post-seismic signatures of the Sumatra 2004 December and 2005 March earthquakes in GRACE satellite gravity

The GRACE satellite mission has been measuring the Earth's gravity field and its temporal variations since 2002 April. Although these variations are mainly due to mass transfer within the geofluid envelops, they also result from mass displacements associated with phenomena including glacial isostatic adjustment and earthquakes. However, these last contributions are difficult to isolate because of the presence of noise and of geofluid signals, and because of GRACE's coarse spatial resolution (>400 km half-wavelength). In this paper, we show that a wavelet analysis on the sphere helps to retrieve earthquake signatures from GRACE geoid products. Using a wavelet analysis of GRACE geoids products, we show that the geoid variations caused by the 2004 December ( M _w= 9.2) and 2005 March ( M _w= 8.7) Sumatra earthquakes can be detected. At GRACE resolution, the 2004 December earthquake produced a strong coseismic decrease of the gravity field in the Andaman Sea, followed by relaxation in the area affected by both the Andaman 2004 and the Nias 2005 earthquakes. We find two characteristic timescales for the relaxation, with a fast variation occurring in the vicinity of the Central Andaman ridge. We discuss our coseismic observations in terms of density changes of crustal and upper-mantle rocks, and of the vertical displacements in the Andaman Sea. We interpret the post-seismic signal in terms of the viscoelastic response of the Earth's mantle. The transient component of the relaxation may indicate the presence of hot, viscous material beneath the active Central Andaman Basin.     

西部1:50000地形图测绘项目技术方案探讨

结合目前国内、国外先进的测绘技术 ,探讨了我国西部沙漠、高山地区测绘地形图的技术方案 ,从而为我国西部困难地区测绘提供可行的技术路线。     

遥感和GIS技术在全球海面风速分析中的应用

将遥感技术和地理信息系统（GIS）技术相结合，建立了一个基于TOPEX卫星的全球海面风速分析的海洋地理信息系统（MGIS）。阐述了全球海面风速分析模型的建立方法，定义了描述风场特征的相关参数，介绍了全球海面风速海洋地理信息系统的结构、功能和工作流程，另外，对系统的3个应用实例进行了地学分析。     

我国资源卫星资料应用对空间分辨率的需求

在简介了我国3种对地遥感卫星的基础上,归纳出我国主要应用领域对遥感图像空间分辨率的需求状况。     

GMS气象卫星在暴雨灾害遥感监测中的应用

利用时空分辨率较高的GMS-5红外、可见光和水汽多通道遥感资料,给出了影响山东省夏季暴雨的卫星遥感图像模型。结合常规气象资料,探索了利用气象卫星遥感资料监测暴雨灾害的方法。     

Possibilities of GPS Kinematic Measurements for Geological Survey in East Slovakia

This paper deals with transformation procedures for observed GPS data from the world geodetic system WGS-84 into the national geodetic grid datum S-UTCN(system of united trigonometric cadaster network) and Baa(the Baltic Sea after adjustment).Transformation from WGS-84 into SUTCN is performed most frequently by means of the 7-element Helmert transformation with three identical points.Geodetic network was adjusted by two ways.     

由空间直角坐标计算大地坐标的简便公式

对大地测量教科书中给出的空间三维直角坐标与大地坐标的转换公式进行了大量的计算与分析，总结得出一组由空间直角坐标计算大地坐标的简便公式。     

一种提高CCD成像卫星空间分辨率的方法研究

从卫星硬件设计与地面软件处理相结合的角度出发，建立了一套提高卫星图像空间分辨率的方法。对模拟靶标图像、一航景物图像、遥感图像分别进行了不同分辨率成像效果的计算机模拟。结果表明，所建立的卫星图像空间分辨率提高理论是正确的，使卫星图像空间分辨率提高2倍甚至更多在理论上是可行的。这一研究成果的实际应用，将会提高卫星的空间分辨率，也可以在保持卫星分辨率的条件下，缩小光学仪器的焦距，使卫星相机小型化，减小其体积和重量。