Geomagnetic Pc3 Pulsations During the Total Solar Eclipse on Aug 11, 1999

The solar eclipse on August 11, 1999, observed in the region covered by many geomagnetic observatories, has offered a unique opportunity to look for an effect of the eclipse on geomagnetic pulsations. The pulsation activity digital data have been taken from Budkov Observatory in the Czech Republic (in the X component only), from observatories in Germany (Niemegk, Fürstenfeldbruck, Bad Bergzabern), in Hungary (Nagycenk), and for comparison in South Africa (Hermanus, conjugate-point station), and in Finland (Sodankylä, far from the eclipse zone). At all these stations the field in all three component has been recorded. The pulsation amplitudes in the X component exhibit a long-term minimum near the time of the eclipse. Spectral analysis of selected short intervals confirmed this decrease and also revealed a decrease of the average pulsation period during the eclipse. Such a change in the amplitude or in the period was not observed outside of the eclipse interval or in other days. Investigation in some narrower frequency bands showed that the maximal decrease occurred in the 15–20 s band. All these changes can be found in records from all the stations near the eclipse totality belt, also in records at the conjugate-point station, where no eclipse occurred. No signature has been found in records at the station situated far from the eclipse zone.     

地磁测量及其应用

地磁已广泛应用于地球科学、航天航空、交通通讯、地震预测、空间天气等诸多领域。鉴于地磁测量是地磁应用的基础，本文分析了现代地磁测量及其研究概况，展望了地磁应用发展趋势。     

温度、湿度对地磁Z基线值的影响及分析

仪器墩体受潮湿影响所产生的局部形变而引起的ZB磁变仪倾斜,是引起成都台CB3ZB变化幅度大,形成N字型年变化及其它类似形态变化的主要原因。实践证明,水泥墩湿引起的形变大,防潮效果差。而质地单纯均匀的石头墩受潮湿后引起的形变小,防潮效果好。     

EXPERIMENTS OF A REDUCED GRID IN LASG/IAPWORLD OCEAN GENERAL CIRCULATION MODELS (OGCMs)

Due to the decrease in grid size associated with the convergence of meridians toward the poles in spherical coordinates, the time steps in many global climate models with finite-difference method are restricted to be unpleasantly small. To overcome the problem, a reduced grid is introduced to LASG/IAP world ocean general circulation models. The reduced grid is implemented successfully in the coarser resolutions version model L30T63 at first. Then, it is carried out in the improved version model LICOM with finer resolutions. In the experiment with model L30T63, under time step unchanged though, execution time per single model run is shortened significantly owing to the decrease of grid number and filtering execution in high latitudes. Results from additional experiments with L30T63 show that the time step of integration can be quadrupled at most in reduced grid with refinement ratio 3. In the experiment with model LICOM and with the model’s original time step unchanged, the model covered area is extended to the whole globe from its original case with the grid point of North Pole considered as an isolated island and the results of experiment are shown to be acceptable.     

The Spatial and Temporal Characteristics of Pc3 Geomagnetic Activity over Canada in 2000, as a Guide to Planning the Times of Aeromagnetic Surveys

Geomagnetic activity affects aeromagnetic surveys. Geomagnetic variations are quite complex and can be quantified in different ways. A measure of geomagnetic activity that is useful for planning aeromagnetic surveys is the Pc3 pulsation index developed by the Australian Space Weather Agency. Purposeful to developing guidelines for planning aeromagnetic surveys in Canada, we study the variations in Pc3 index amplitude over Canada in 2000. This study shows distinct patterns associated with the sub-auroral zone, the auroral zone, and the polar cap. Average Pc3 index activity is higher during the months of February, July, September, and November in the auroral and sub-auroral zones. The station in the polar cap exhibits maximum activity near midday during the summer months. Detailed analysis of a magnetic storm shows that Pc3 index amplitude during the beginning of the solar storm is least important at the polar cap. The mean Pc3 index also relates to solar wind parameters such as the solar wind velocity and the vertical polarity of the interplanetary magnetic field. Analysis of the morning maximum of the Pc3 index observed in the auroral zone can be used to develop guidelines for planning aeromagnetic surveys in Canada and other areas of the world affected by auroral zones.     

大庆采油一厂GIS数据查询与维护模块的设计与实现

利用VB在GeoStar地理信息系统开发平台上进行二次开发,实现大庆油田采油一厂水泡子地理信息系统的3维数据查询与维护。介绍了系统的模块组成和功能,以及实现各项功能的关键技术。该系统灵活实用、功能较全,通过实际生产应用,反映出在地面水域地理信息数据计算与管理、直观显示等方面具有很好的实用价值。     

Derivatives of the Gravity Potential with Respect to Rectangular Coordinates

Starting from a complex operator of derivation, we give expressions for derivatives of arbitrary order of the gravity potential with respect to rectangular coordinates. These expressions have a form similar to the original potential expanded in spherical harmonics and are free of singularity at the poles. Computing sets of numerical coefficients once for all, we can compute the derivatives with a very limited work: the same functions are used to compute all derivatives by means of a unique parametrized formula. This is very comfortable for further algebraic manipulations. Numerical tests prove the accuracy and the efficiency of the algorithm derived from our formula to compute the gravity acceleration vector and the gravity gradient tensor.     

运用GPS测量对自贡市城市控制网点的改算

本文通过对运用GPS测量改算自贡市各等级城市控制网点成果的过程及结果的论述分析,证实了运用GPS测量改算城市控制网点成果具有精度好、效率高等特点。在此基础上探讨其可行性,并提出一些看法。     

对AE指数的讨论：是否适用于磁层相空间重构

分析表明,目前广泛应用的ＡＥ指数虽然在一定程度能反映极区地磁活动特征,但其物理意义不清,不能描述亚暴活动的物理过程,不宜用来作磁层相空间重构等非线性过程的研究。ＡＵ和ＡＬ虽是不可缺少的描述极光电集流活动的指数,但仍须消除规则日变化ＳＲ的影响、改进推导方法（和台站布局）。