High frequency of occurrence of large solar energetic particle events prior to 1958 and a possible repetition in the near future
High frequency of occurrence of large solar energetic particle events prior to 1958 and a possible repetition in the near future
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1958 年之前大型太阳高能粒子事件发生频率较高，并且在不久的将来可能会重复发生
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
K. Mccracken
中科院分区：
文献类型：
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作者：
K. Mccracken
结果表明，1958年之前，大于4GeV的大型太阳高能粒子事件的注量是空间时代的10倍，发生频率是空间时代的4倍。1946年和1949年有两次事件的能量密度大于4 GeV，与1956年2月23日的相似，这意味着在相似的时间段内，最大可能事件的能量密度大于4 GeV。历史上的宇宙射线和冰川学记录表明，在高能量和低能量的情况下，这种大型事件发生的通量和概率在低长期太阳活动和与估计的日光层磁场强度相关的时间段内最大。本文提出了一个工作模型，其中控制大SEP事件发生的因素是（1）大太阳耀斑或CME的发生和（2）地球附近日磁场<6.5nT。讨论了该模型的理论基础。有人提出，下一个Gleissberg极小期的太阳活动将导致重复1958年前的高频率，高通量GLE和SEP事件。本文提出了两个预测SEP活动增强的指标：（1）与1954年相比，在太阳活动极小期的最大中子监测率上升>5%;（2）在新的太阳活动周期中，地球附近测得的日磁场在≥2年内保持<6.5 nT，或者在太阳黑子活动极小期基本上小于5 nT。
It is shown that the >4 GeV fluence of large solar energetic particle events was a factor of 10 greater and the frequency of occurrence a factor of four greater prior to 1958 than during the space era. There were two events in 1946 and 1949 with >4 GeV fluences similar to that of 23 February 1956, suggesting that the >4 GeV fluence of the largest probable event for a similar period would be ∼3 times greater. The historic cosmic ray and glaciological records indicate that the fluences and probability of occurrence of such large events at both high and low energies are greatest in periods of low long‐term solar activity and anticorrelated with the estimated strength of the heliospheric magnetic field. A working model is proposed where the factors controlling the occurrence of large SEP events are (1) the occurrence of a large solar flare or CME and (2) the heliomagnetic field being <6.5 nT near Earth. A theoretical basis for this model is discussed. It is proposed that the next Gleissberg minimum of solar activity will lead to a repetition of the pre‐1958 era of high‐frequency, high‐fluence GLE and SEP events. Two predictive indicators of higher SEP activity are proposed: (1) the Climax neutron monitor rate at solar minimum rises >5% compared to 1954 and (2) the measured heliomagnetic field near Earth remains <6.5 nT for ≥2 years into a new solar cycle, or alternatively it is substantially less than 5 nT at sunspot minimum.