Optimal piecewise regression analysis and its application to geomagnetic time series
Optimal piecewise regression analysis and its application to geomagnetic time series
复制标题
最优分段回归分析及其在地磁时间序列中的应用
DOI：
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
K. Whaler
中科院分区：
文献类型：
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作者：
D. Stewart;K. Whaler
总结
SUMMARY
The geomagnetic secular variation of declination at many observatories in Europe is approximately two straight lines, with a sudden and marked change in slope at around 1969. Different components of the field at other observatories show a similar change at around the same time, and there are suggestions of the same phenomenon, commonly referred to as a geomagnetic impulse, having occurred at other epochs. Modelling of geomagnetic observatory records has usually assumed that an impulse occurred, and specified its date, making the analysis somewhat subjective. Here we present a new algorithm, using regression, which tests the hypothesis of quadratic time dependence of the field over all possible time intervals, ranking them such that the data series are modelled by the fewest such quadratics (i.e. the smallest number of parameters) that provide an adequate fit to the data. In this way, the dates of any impulses are determined objectively, rather than imposed a priori, and the adequacy of quadratic time dependence is assessed. The method is tested on synthetic data, and then applied to a total of 5766 vector annual means of geomagnetic data from 119 observatories.