Tracking a non-dipole geomagnetic anomaly using new archaeointensity results from north-east China

A collection of ceramics and samples, collected from north-east China with ages ranging from 1000 to 7000 years, have been investigated using a modified version of the Shaw palaeointensity techniques (Shaw 1974; Rolph & Shaw 1985) in which only partial NRMs and TRMs (PNRMs and PTRMs) with blocking temperatures (T_b) above 300 C are used after pre-selection of samples by mineral magnetic analysis. A secular variation curve obtained from this study is quite consistent with previous results from other areas of China (Wei et al. 1987; Tang et al. 1991), as well as with the global model of McElhinny & Senanayake (1982). Comparison of the Chinese results with contemporaneous results from Greece (Aitken et al. 1989) has allowed us to track the movement of a large non-dipole anomaly as it drifts westwards.     

中国低纬地区地磁变化与赤道电射流

根据资料分析了中国低纬地区地磁场Ｈ分量的静日变化规律。结果表明，Ｈ分量日变幅在中午１２点左右达到最大值，在夜间达到最小值，而且，这种受赤道电射流影响的现象还随着季节和太阳活动变化而变化。     

地磁数据处理软件

如何应用微机对地磁观测数据进行处理，是运用现代方法处理地磁资料的一个关键问题。本文在实践（该软件已试用一年）的基础上，研制出了一种新的数据处理软件，代替了传统的手工计算。该软件应用ＢＡＳＩＣ语言编写，主要功能包括：①同现有的野外地磁测量的记录软件（ＰＣ－１５００计算机）联网；②计算各个测点总场强度和垂直强度（含主测点和副测点）的桩位差与仪器差、桩位差和仪器差的均方误差、通化差、通化均方误差、本期差值、相邻差值、点变幅减变幅均值、点变幅减变幅均相邻差值及各种精度的统计；③数据的分类、查询、替换、存储；④３种汉化的成果报表。     

东亚地磁场的Taylor多项式模型

根据我国国家自然科学基金委员会和俄罗斯科学院的国际合作研究计划，在国际上首次同时使用中国、前苏联和蒙古的地磁复测点资料，以及东亚地区的地磁台站资料，计算出１９８０．０年东亚地磁场的Ｔａｙｌｏｒ多项式模型，并绘制出相应的东亚地磁图，给出了确定地磁场模型最大阶数的新判据。     

Geomagnetically induced currents in the Finnish high-voltage power system

We consider geomagnetically induced currents (GICs) in power systems from the viewpoint of a geophysicist. Special attention is paid to the Finnish high-voltage power system, in which exact theoretical model calculations together with recordings have been performed for several years. We present several examples of theoretically computed GICs using different geophysical models for estimating the geoelectric field driving GICs. Statistical prediction of GICs is outlined referring to studies made in Finland. We show that a combination of GIC recordings at few sites with theoretical modelling of ionospheric currents and the earth's conductivity, and data of geomagnetic activity makes it possible to derive GIC statistics of the entire power system. Finally, we discuss requirements for a long-range prediction of GICs, which will obviously be a widely-studied topic in future.