1 Institute of Geophysics, China Earthquake Administration, Beijing 100081, China 2 Chongming Observatory, Earthquake Administration of Shanghai Municipality, Shanghai 202164, China 3 Beijing Observatory, Institute of Geophysics, China Earthquake Administration, Beijing 100095, China
Statistical study on great geomagnetic storms during solar cycle 23
1 Institute of Geophysics, China Earthquake Administration, Beijing 100081, China 2 Chongming Observatory, Earthquake Administration of Shanghai Municipality, Shanghai 202164, China 3 Beijing Observatory, Institute of Geophysics, China Earthquake Administration, Beijing 100095, China
摘要Characteristics of great geomagnetic storms during solar cycle 23 were statistically investigated. Firstly, we focused on the uniqueness of solar cycle 23 by analyzing both the great storm number and sunspot number from 1957 to 2008. It was found that the relationship between the sunspot number and great storm number weakened as the activity of the storms strengthened. There was no obvious relationship between the annual sunspot number and great storm number with Dst≤?300 nT. Secondly, we studied the relationship between the peak Dst and peak Bz in detail. It was found that the condition Bz≤?10 nT is not necessary for storms with Dst≤?100 nT, but seems necessary for storms with Dst≤?150 nT. The duration for Bz≤?10 nT has no direct relationship with the giant storm. The correlation coefficient between the Dst peak and Bz peak for the 89 storms studied is 0.81. After removing the effect of solar wind dynamic pressure on the Dst peak, we obtained a better correlation coefficient of 0.86. We also found the difference between the Dst peak and the corrected Dst peak was proportional to the Dst peak.
Abstract：Characteristics of great geomagnetic storms during solar cycle 23 were statistically investigated. Firstly, we focused on the uniqueness of solar cycle 23 by analyzing both the great storm number and sunspot number from 1957 to 2008. It was found that the relationship between the sunspot number and great storm number weakened as the activity of the storms strengthened. There was no obvious relationship between the annual sunspot number and great storm number with Dst≤?300 nT. Secondly, we studied the relationship between the peak Dst and peak Bz in detail. It was found that the condition Bz≤?10 nT is not necessary for storms with Dst≤?100 nT, but seems necessary for storms with Dst≤?150 nT. The duration for Bz≤?10 nT has no direct relationship with the giant storm. The correlation coefficient between the Dst peak and Bz peak for the 89 storms studied is 0.81. After removing the effect of solar wind dynamic pressure on the Dst peak, we obtained a better correlation coefficient of 0.86. We also found the difference between the Dst peak and the corrected Dst peak was proportional to the Dst peak.
基金资助:the project Environment Building for S&T Industries (2005DKA64000)
通讯作者:
Qi Li
E-mail: darcyli@163.com
引用本文:
Qi Li, Yufen Gao, Peiyu Zhu, Huaran Chen, Xiuling Zhang. Statistical study on great geomagnetic storms during solar cycle 23[J]. 《地震学报》英文版, 2011, 24(4): 365-372.
Qi Li, Yufen Gao, Peiyu Zhu, Huaran Chen, Xiuling Zhang. Statistical study on great geomagnetic storms during solar cycle 23. Earthquake Science, 2011, 24(4): 365-372.
