| 其他摘要 | The sun is the nearest star to the earth and human.The solar wind is an important medium through which the sun can impact the earth and influence space weather. Since the solar wind was first measured at last century, the origin of the solar wind , the properties of the solar wind , and the way how they connect with their source regions and acceleration mechanism are important both as a fundamental issue in solar physics and space physics. Firstly, the solar wind background knowledge and research status of solar wind cycle behaviors are introduced briefly. Then the statistical characteristic analysis of solar wind cycle behaviors is presented in detail. The main result are as follows:Daily mean value of solar wind velocity measured by various spacecraft near the Earth’s orbit from 1963 November 27 to 2013 December 31 given by OMNIWeb is utilized to investigate its characteristics through statistical analyses. The percent probability distribution of solar wind velocity can be described well by the Γ distribution function with the most probable velocity to be 373 km s-1. It is found that solar wind could be statistically classified into three groups: (1) the low-velocity wind, v is less than 450 km s-1 , which positively responds to, and in the cycle phase lags, the solar activity cycle; (2) the high-velocity wind, v is greater than or equal to 450 km s-1 and less than 725 km s-1, which negatively responds to, and in the cycle phase leads, the solar activity cycle, but in a short timescale (one-rotationperiod) lags the solar activity cycle; and (3) the extreme-high-velocity wind,v is greater than or equal to 725 km s-1, which positively responds to, and in cycle phase leads, the solar activity cycle. A period of about 27 days is determined for solar wind in the first two groups, so that solar wind in the groups is modulated by the solar rotation and related with solar long-life magnetic structures. Solar wind of extreme high velocity appears mainly at the descending phases of the solar cycles.Daily mean velocity of solar wind, which was surveyed near the Earth's orbit at about 1 AU from 27 November 1963 to 30 November 2015 and issued by OMNIWeb is used to look into its periodicity through the Lomb - Scargle periodogram method. As the strongest periodical signal, the solar activity cycle of about 10.4 years is found in high-velocity wind, but in low-velocity wind, the 9.17-year cycle appears instead. The rotation cycle of about 27 days and its 1/2and 1/3 harmonic periods are clearly detected in all-, low- and high- velocity wind, and at periodogram several individual periodical peaks appear very close to the peaks of these three periods. The annual period of about 1.07 years is identified for both all- and low- velocity wind, but not for high-velocity wind after 1994. The 1.68-year period occurs in all- and high- velocity wind, but does not appear in low-velocity wind. The period of about 2.42 years appears just in the all-velocity wind after 1994, but its 2-fold period (about 4.83 years) appears in both all- and high- velocity wind. The period of about 4.1 years occurs in all-, low-, and high- velocity wind. The possible origin of these periods is discussed. |
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