中等磁暴太阳周分布的统计研究

依据实际观测的中等磁暴数据,统计分析了中等磁暴的太阳周分布.分析结果表明,在一个太阳活动周内,每年中等磁暴随时间的变化出现多个峰值,其中,最大峰值均出现在太阳活动周的下降段,即中等磁暴的峰值比太阳黑子数平滑年均值的峰值要滞后,滞后的时间为2～3年.超过70%的中等磁暴出现在太阳活动周的下降段,这表明绝大多数中等磁暴出现在太阳活动周的下降段.通过对中等磁暴平滑月均值与太阳黑子数平滑月均值相位差的计算分析发现,中等磁暴峰值出现的时间比太阳黑子数峰值出现的时间要滞后,不同太阳活动周中等磁暴峰值出现的时间与太阳黑子数峰值时间滞后的程度不同.

Statistical Analysis of Solar Cycle Distribution of Moderate Storms

In this paper, the statistical analysis of solar cycle distribution of moderate geomagnetic storms (-100nT< Dst ≤-50nT) is investigated based on observed data. The results show that the yearly number of moderate storms have multi-peaks in each cycle with the highest peak appeared in the descending phase of the cycle. This means that the highest peak of moderate storms have a time lag with respect to the yearly number of sunspot numbers. The time lag is about 2～3 year. More than 70% moderate storms appeared in the descending phase of a solar cycle. During the solar maximum, there are less moderate storms occurred than that occurred in other period of a solar cycle. Monthly mean moderate storm numbers and smoothed monthly mean sunspot numbers is also investigated in this paper. The results show that the time of moderate storms peaks lag behind that of the time of sunspots peaks, the time of peaks of both moderate storms and sunspots is different, and the time differences are different in different solar cycles, ranging from a few years to just a few months.