Modeling the global ionospheric total electron content with empirical orthogonal function analysis
Modeling the global ionospheric total electron content with empirical orthogonal function analysis
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DOI：
10.1007/s11431-012-4823-8
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发表时间：
2012-03
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影响因子：
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通讯作者：
W. Wan;F. Ding;Z. Ren;Man‐Lian Zhang;Libo Liu;B. Ning
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文献类型：
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作者：
W. Wan;F. Ding;Z. Ren;Man‐Lian Zhang;Libo Liu;B. Ning
在目前的工作中，我们模拟全球电离层总电子含量（TEC）的经验正交函数（ERF）的分析。所得到的统计特征模由两个因素组成：在经纬度（或当地时间LT）上映射TEC模式的特征向量，以及在不同时间尺度上显示TEC变化的相应系数，即，太阳活动周期、年（一年和半年）和昼夜的世界时变化。结果表明，电离层TEC变化的模态分析可以将TEC变化分解为主要的过程，前两个模态反映了电离层的主要气候特征。第一模态既包含表示半年异常的半年分量，又包含表示年或非季节异常的年分量。第二模态主要包含年分量，并显示了大多数纬度和当地时间扇区的正常季节性电离层变化。第二模态的年分量也反映了中午前后中高纬度地区电离层的季节性异常。结果表明，作为一种统计本征模方法，该方法在电离层气候学分析中是有效的，可用于建立电离层气候学的经验模型。
In the present work we model the global ionospheric total electron content (TEC) with the analysis of empirical orthogonal functions (EOF). The obtained statistical eigen modes, which makeup the modeled TEC, consist of two factors: the eigen vectors mapping TEC patterns at latitude and longitude (or local time LT), and the corresponding coefficients displaying the TEC variations in different time scales, i.e., the solar cycle, the yearly (annual and semiannual) and the diurnal universal time variations. It is found that the EOF analysis can separate the TEC variations into chief processes and the first two modes illustrate the most of the ionospheric climate properties. The first mode contains both the semiannual component which shows the semiannual ionospheric anomaly and the annual component which shows the annual or non-seasonal ionospheric anomaly. The second mode contains mainly the annual component and shows the normal seasonal ionospheric variation at most latitudes and local time sectors. The annual component in the second mode also manifests seasonal anomaly of the ionosphere at higher mid-latitudes around noontime. It is concluded that the EOF analysis, as a statistical eigen mode method, is resultful in analyzing the ionospheric climatology hence can be used to construct the empirical model for the ionospheric climatology.