Solar cycle distribution of major geomagnetic storms  

作　　者：Gui-Ming Le Zi-Yu Cai Hua-Ning Wang Zhi-Qiang Yin Peng Li 

机构地区：[1]National Center for Space Weather, China Meteorological Administration [2]Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences [3]Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education [4]The Second High School Attached to Beijing Normal University [5]Nanjing University of Information Science & Technology

出　　处：《Research in Astronomy and Astrophysics》2013年第6期739-748,共10页天文和天体物理学研究（英文版）

基　　金：supported by the National Basic Research Program of China (973 Program, Grant Nos. 2012CB957801 and 2011CB811406);the National Natural Science Foundation of China (Grant Nos. 41074132, 41274193 and 40931056);the National Standard Research Program (Grant No. 10-123)

摘　　要：We examine the solar cycle distribution of major geomagnetic storms （Dst ≤ -100 nT）, including intense storms at the level of -200 nT〈 Dst ≤ -100 nT, great storms at -300 nT〈 Dst ≤-200 nT, and super storms at Dst ≤ -300 nT, which occurred during the period of 1957-2006, based on Dst indices and smoothed monthly sunspot numbers. Statistics show that the majority （82%） of the geomagnetic storms at the level of Dst≤ -100 nT that occurred in the study pe- riod were intense geomagnetic storms, with 12.4% ranked as great storms and 5.6% as super storms. It is interesting to note that about 27% of the geomagnetic storms that occurred at all three intensity levels appeared in the ascending phase of a solar cycle, and about 73% in the descending one. Statistics also show that 76.9% of the intense storms, 79.6% of the great storms and 90.9% of the super storms occurred during the two years before a solar cycle reached its peak, or in the three years after it. The correlation between the size of a solar cycle and the percentage of major storms that occurred, during the period from two years prior to maximum to three years af- ter it, is investigated. Finally, the properties of the multi-peak distribution for major geomagnetic storms in each solar cycle is investigated.We examine the solar cycle distribution of major geomagnetic storms （Dst ≤ -100 nT）, including intense storms at the level of -200 nT〈 Dst ≤ -100 nT, great storms at -300 nT〈 Dst ≤-200 nT, and super storms at Dst ≤ -300 nT, which occurred during the period of 1957-2006, based on Dst indices and smoothed monthly sunspot numbers. Statistics show that the majority （82%） of the geomagnetic storms at the level of Dst≤ -100 nT that occurred in the study pe- riod were intense geomagnetic storms, with 12.4% ranked as great storms and 5.6% as super storms. It is interesting to note that about 27% of the geomagnetic storms that occurred at all three intensity levels appeared in the ascending phase of a solar cycle, and about 73% in the descending one. Statistics also show that 76.9% of the intense storms, 79.6% of the great storms and 90.9% of the super storms occurred during the two years before a solar cycle reached its peak, or in the three years after it. The correlation between the size of a solar cycle and the percentage of major storms that occurred, during the period from two years prior to maximum to three years af- ter it, is investigated. Finally, the properties of the multi-peak distribution for major geomagnetic storms in each solar cycle is investigated.

关 键 词：SUN sunspots -- Sun activity -- Sun solar-terrestrial relations 

分 类 号：P182.9[天文地球—天文学]