The descent of the solar Cycle 24 and future space weather

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• 作者：H.S. Ahluwalia ^{hsa@unm.edu" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Sunspots ; Cycle 24 ; F10.7 ; Space weather
• 刊名：Advances in Space Research
• 出版年：2016
• 出版时间：15 January 2016
• 年：2016
• 卷：57
• 期：2
• 页码：710-714
• 全文大小：349 K

文摘

We study the development of the Cycle 24 using the recently revised sunspot number (SSN) time series proposed by Clette et al. (2014) labeled SSN (V2). The smooth SSN for the cycle increased since its onset in December 2008, developing a shoulder in 2012, a plateau in 2013 and a peak in 2014, a behavior similar to the Cycle 15 that reached a plateau and rose to a much higher peak. Present status of the Cycle 24 is described in terms of SSN (V2) and 10.7 cm (2800 MHz) microwave flux (F10.7) from the sun and its activity is compared to some prior cycles of the nineteenth and twentieth century. SSNs declined at a faster rate than F10.7 starting near the Cycle 21 minimum reaching the peak 2 months after the SSN peak. The physical cause(s) for these differences is not known. The decay phase for both indices has set in. The historic evidence suggests that the Cycle 25 may be less than half as active as the Cycle 24 with a longer duration leading to a reduced in size heliosphere and a significant decrease in the phenomena that track SSNs at 1 AU, such as: the intensity (B) of the interplanetary magnetic field (IMF), the frequency of the fast coronal mass ejections (CMEs), the storm sudden commencements and the large Forbush decreases accompanied by a significant increase in the low energy galactic cosmic rays (GCRs) and reduced disturbances in the ionosphere; even so one cannot rule out the occurrence of an extreme CME in future.