Automated detection of Pi 2 pulsations using wavelet analysis: 1. Method and an application for substorm monitoring
Automated detection of Pi 2 pulsations using wavelet analysis: 1. Method and an application for substorm monitoring
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使用小波分析自动检测 Pi 2 脉动：1. 亚暴监测方法和应用
DOI：
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
N. Sumitomo
中科院分区：
文献类型：
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作者：
M. Nosé;T. Iyemori;M. Takeda;T. Kamei;D. Milling;D. Orr;H. Singer;E. W. Worthington;N. Sumitomo
小波分析适用于研究波，如Pi 2脉动，这是有限的时间和频率。我们已经开发了一种算法来检测Pi 2脉动的小波分析。我们对该算法进行了测试，发现Pi 2检测的结果与视觉检测的结果一致。该算法被应用于一个项目，其目的是在临近预报的亚暴爆发。在这个项目中，我们使用在中低纬度台站（日本的Mineyama，英国的约克SAMNET台站，美国的Boulder）。这些观测站在经度上相隔约120°，因此至少有一个观测站一直在夜面。我们计划使用Pi 2检测算法分析每个站点的实时数据，并通过互联网在这些站点之间交换检测结果。因此，我们可以实时获得亚暴爆发的信息，即使我们在白昼。我们已经在峰山天文台建立了一个自动检测π 2脉动的系统。1996年2月至8月的观测结果表明，π 2脉动的探测成功率，夜侧（18- 06 MLT）为83.4%，昼侧（06- 18 MLT）为26.5%。在当地午夜（20- 02 MLT）附近的检测结果显示，检测成功率为93.2%。
Wavelet analysis is suitable for investigating waves, such as Pi 2 pulsations, which are limited in both time and frequency. We have developed an algorithm to detect Pi 2 pulsations by wavelet analysis. We tested the algorithm and found that the results of Pi 2 detection are consistent with those obtained by visual inspection. The algorithm is applied in a project which aims at the nowcasting of substorm onsets. In this project we use real-time geomagnetic field data, with a sampling rate of 1 second, obtained at mid- and low-latitude stations (Mineyama in Japan, the York SAMNET station in the U.K., and Boulder in the U.S.). These stations are each separated by about 120° in longitude, so at least one station is on the nightside at all times. We plan to analyze the real-time data at each station using the Pi 2 detection algorithm, and to exchange the detection results among these stations via the Internet. Therefore we can obtain information about substorm onsets in real-time, even if we are on the dayside. We have constructed a system to detect Pi 2 pulsations automatically at Mineyama observatory. The detection results for the period of February to August 1996 showed that the rate of successful detection of Pi 2 pulsations was 83.4% for the nightside (18-06MLT) and 26.5% for the dayside (06-18MLT). The detection results near local midnight (20-02MLT) give the rate of successful detection of 93.2%.