Statistical analysis of solar H-alpha flares
Statistical analysis of solar H-alpha flares
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DOI：
10.1051/0004-6361:20010908
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发表时间：
2001-09
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影响因子：
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通讯作者：
M. Temmer;A. Veronig;A. Hanslmeier;W. Otruba;M. Messerotti
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文献类型：
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作者：
M. Temmer;A. Veronig;A. Hanslmeier;W. Otruba;M. Messerotti
本文对1975年1月至1999年12月期间发生的H-α耀斑的一个大型数据集进行了统计分析，其中包括近100000个单次事件。我们分析了耀斑的演化步骤，即持续时间、上升时间、衰变时间和事件不对称性。此外，还分析了表征耀斑时间行为的参数以及太阳圆盘上的空间分布，即N-S和E-W不对称，以及它们对太阳周期的依赖关系。主要研究结果如下：1)持续期、上升和下降时间随着重要性等级的增加而增加。衰变时间的增加比上升时间的增加更明显。同样的关系对于亮度等级也是有效的，但以较弱的方式。2)表征事件衰变时间与上升时间比例的事件不对称指数主要为正值(90%)。对于大约50%的事件，衰变时间甚至是上升时间的4倍以上。3)事件的不对称性随着重要性等级的增加而增加。4)耀斑持续时间和衰变时间随太阳周期而变化，上升时间与太阳周期变化不同。5)事件不对称性与太阳活动周期没有明显的相关性。然而，它们在太阳活动最小的时候下降，这可以用最小活动期间发现的较短的衰变时间来解释。6)在较长的周期内存在显著的N-S不对称性，并且一个半球对另一个半球的优势可以持续一个以上的周期。7)对于某些周期，可能有证据表明N-S不对称性随着太阳周期的变化而演化，但总体上并非如此。8)存在轻微但显著的东西向不对称性，东部超额度延长。
A statistical analysis of a large data set of H-alpha flares comprising almost 100000 single events that occurred during the period January 1975 to December 1999 is presented. We analyzed the flares evolution steps, i.e. duration, rise times, decay times and event asymmetries. Moreover, these parameters characterizing the temporal behavior of flares, as well as the spatial distribution on the solar disk, i.e. N-S and E-W asymmetries, are analyzed in terms of their dependency on the solar cycle. The main results are: 1) The duration, rise and decay times increase with increasing importance class. The increase is more pronounced for the decay times than for the rise times. The same relation is valid with regard to the brightness classes but in a weaker manner. 2) The event asymmetry indices, which characterize the proportion of the decay to the rise time of an event, are predominantly positive (90%). For about 50% of the events the decay time is even more than 4 times as long as the rise time. 3) The event asymmetries increase with the importance class. 4) The flare duration and decay times vary in phase with the solar cycle; the rise times do not. 5) The event asymmetries do not reveal a distinct correlation with the solar cycle. However, they drop during times of solar minima, which can be explained by the shorter decay times found during minimum activity. 6) There exists a significant N-S asymmetry over longer periods, and the dominance of one hemisphere over the other can persist for more than one cycle. 7) For certain cycles there may be evidence that the N-S asymmetry evolves with the solar cycle, but in general this is not the case. 8) There exists a slight but significant E-W asymmetry with a prolonged eastern excess.