Diurnal and seasonal occurrence of polar patches
Diurnal and seasonal occurrence of polar patches
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极地斑块的昼夜和季节性发生
DOI：
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发表时间：
1996
期刊：
影响因子：
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通讯作者：
A. Graham
中科院分区：
文献类型：
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作者：
A. Rodger;A. Graham
对极地斑块日间和季节性变化的分析（根据南极洲哈雷近两年黑子最大值期间的高频雷达数据确定）表明，在磁正午（而不是当地正午）附近出现了一个广泛的最大值。盛夏和隆冬附近发生最少，春分到冬季期间最多。极地斑块的出现与相应的太阳风和IMF参数的小时平均值之间没有显着的相关性，除了斑块通常在行星际磁场具有南向分量时出现。结果可以根据 UT 和从白天电离层对流到极冠的血浆浓度的季节差异来理解。在夏季和冬季，极冠中的电子浓度分别较高和较低，但相对无结构。春分左右，电离增强的舌状物对流到极冠；然后，这个舌头是通过行星际磁场的影响而构造的，但是这些哈雷数据不能用于区分斑块形成的各种竞争机制。观察到的极地斑块发生的昼夜和季节变化与Sojka等人的预测基本一致。 （1994）当他们的结果被翻译到南半球时。然而，通量传输事件的电离层效应仍然被认为对其形成至关重要，这一特征尚未包含在 Sojka 等人的研究中。模型。
Analysis of the diurnal and seasonal variation of polar patches, as identified in two years of HF-radar data from Halley, Antarctica during a period near sunspot maximum, shows that there is a broad maximum in occurrence centred about magnetic noon, not local noon. There are minima in occurrence near midsummer and midwinter, with maxima in occurrence between equinox and winter. There are no significant correlations between the occurrence of polar patches and the corresponding hourly averages of the solar wind and IMF parameters, except that patches usually occur when the interplanetary magnetic field has a southward component. The results can be understood in terms of UT and seasonal differences in the plasma concentration being convected from the dayside ionosphere into the polar cap. In summer and winter the electron concentrations in the polar cap are high and low, respectively, but relatively unstructured. About equinox, a tongue of enhanced ionisation is convected into the polar cap; this tongue is then structured by the effects of the interplanetary magnetic field, but these Halley data cannot be used to separate the various competing mechanisms for patch formation. The observed diurnal and seasonal variation in the occurrence of polar patches are largely consistent with predictions of Sojka et al. (1994) when their results are translated into the southern hemisphere. However, the ionospheric effects of flux transfer events are still considered essential in their formation, a feature not yet included in the Sojka et al. model.