Improvement of satellite data main field modelling through a better separation of internal from external contributions

通过更好地分离内部和外部贡献来改进卫星数据主场建模

• 批准号: 5370220
• 负责人: Professor Dr. Hermann Lühr
• 金额: --
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2002
• 资助国家: 德国
• 起止时间: 2001-12-31 至 2007-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5370220?language=en
• 关键词: Improvement; satellite; data; main; field

Determining the geomagnetic secular variation from satellite magnetic field measurements requires the repeated generation of main field models for different epochs separated by about a month. From the changes in the Gauss coefficients of successive field models the secular variation are derived. This procedure puts high demands on the quality of the models, since any spurious effect may mimic a variation. With the launch of the CHAMP satellite on 15th July 2000 highly accurate magnetic field measurements have become available. The long designed life-time of 5 years and the low polar orbit make this data set particularly useful for secular variation studies. In order to utilise the full accuracy for main field modelling special attention has to be paid to a correct removal of the magnetic contribution from ionospheric currents. Particulary challenging are the high latitudes. Here substantional currents are flowing even on the night side and during magnetically quiet days. In the past little has been done to further improve this situation. In this proposal we plan to model the ionospheric currents in the polar regions by combining ground-based and space-based observations. The aim is to construct a description of ionospheric currents for quiet periods, which is controlled by ground-based and solar wind observations and which can be used to correct the CHAMP magnetic field data prior to main field modelling.

根据卫星磁场测量确定地磁长期变化需要针对相隔大约一个月的不同历元重复生成主磁场模型。从连续场模型高斯系数的变化可以得出长期变化。该过程对模型的质量提出了很高的要求，因为任何寄生效应都可能模仿变化。随着 2000 年 7 月 15 日 CHAMP 卫星的发射，高精度的磁场测量已经成为可能。 5 年的超长设计寿命和低极轨道使得该数据集对于长期变化研究特别有用。为了充分利用主场建模的精度，必须特别注意正确去除电离层电流的磁贡献。高纬度地区尤其具有挑战性。即使在夜间和磁力安静的白天，这里也会有大量电流流动。过去，几乎没有采取任何措施来进一步改善这种情况。在该提案中，我们计划通过结合地面和空间观测来模拟极地地区的电离层电流。目的是构建对安静时期电离层电流的描述，该描述由地面和太阳风观测控制，并可用于在主场建模之前校正 CHAMP 磁场数据。