Harmonic quiet-day curves as magnetometer baselines for ionospheric current analyses
Harmonic quiet-day curves as magnetometer baselines for ionospheric current analyses
复制标题
谐波静日曲线作为电离层电流分析的磁力计基线
DOI：
10.5194/gi-2-289-2013
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
M. Kamp
中科院分区：
文献类型：
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作者：
M. Kamp
抽象的。本文提出了一种确定磁力计数据基线的新方法。该基线由与电离层和磁层扰动无关的所有磁场分量组成，即由于太阳安静变化和其他背景变化（例如潮汐和长期变化）以及设备影响而引起的所有场分量。当分析太阳扰动引起的磁场变化时，提取该基线非常有用。这使得磁力计数据适用于计算与地磁暴和亚暴相关的电离层等效电流。完整基线主要由两个主要组成部分组成：每日基线和长期基线。对于每日基线，根据最安静的日子中每日曲线的最低几个谐波导出第一个“模板”。基线的日变化是通过这些模板之间的线性插值获得的；这种方法可以确保始终保持平稳的基线，避免几天之间过渡时出现任何不连续性。长期基线是通过每日数据中值之间的线性插值得到的；这样可以确保基线遵循长期趋势，例如季节性和潮汐变化以及设备漂移。除受干扰最严重的日子外，计算所有日子的每日中值；其中包括了这种选择的程序。该方法避免了与传统基线方法和其他一些最近发布的方法相关的许多问题，并且比大多数其他最近发布的方法更简单。据可以比较，去除基线后得到的场的分布与使用其他最近的基线方法的结果场的分布在很大程度上相似。然而，本文方法相对于其他方法的主要优点是，它可以有效地消除设备漂移和其他伪影，而不会丢弃太多数据，因此即使来自远程无人磁力计的低质量数据也可以适合分析。这可以为电离层等效电流数据库做出有价值的贡献，特别是在极冠边界附近的区域。
Abstract. This paper presents a novel method to determine a baseline for magnetometer data. This baseline consists of all magnetic field components not related to ionospheric and magnetospheric disturbances, i.e. all field components due to solar quiet variations and other background variations, such as tidal and secular variations, as well as equipment effects. Extraction of this baseline is useful when the magnetic field variations due to solar disturbances are analysed. This makes magnetometer data suitable, for instance, for the calculation of ionospheric equivalent currents related to geomagnetic storms and substorms. The full baseline is largely composed of two main constituents: the diurnal baseline and the long-term baseline. For the diurnal baseline, first "templates" are derived, based on the lowest few harmonics of the daily curves from the quietest days. The diurnal variation of the baseline is obtained by linear interpolation between these templates; this method ensures a smooth baseline at all times, avoiding any discontinuities at transitions between days. The long-term baseline is obtained by linear interpolation between the daily median values of the data; this way the baseline is ensured to follow long-term trends, such as seasonal and tidal variations, as well as equipment drift. The daily median values are calculated for all days except the most disturbed ones; a procedure for this selection is included. The method avoids many problems associated with traditional baseline methods and some of the other recently published methods, and is simpler in procedure than most other recent ones. As far as can be compared, the distribution of the resulting field after removal of the baseline is largely similar to that using other recent baseline methods. However, the main advantage of the method of this paper over others is that it removes equipment drift and other artefacts efficiently without discarding too much data, so that even low-quality data from remote unmanned magnetometers can be made suitable for analysis. This can give valuable contributions to the database of ionospheric equivalent currents, especially in the area near the polar cap boundary.
地基磁场观测获得的方电流结构分析
DOI：
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发表时间：
2007
期刊：
影响因子：
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作者：
Hiroko Kohta;et. al.
通讯作者：
et. al.