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Solar Wind Speed and Expansion Rate of the Coronal Magnetic Field in Solar Maximum and Minimum Phases

机译：太阳最大相位和最小相位中太阳风的速度和日冕磁场的膨胀率

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Relationships between solar wind speed and expansion rate of the coronal magnetic field have been studied mainly by in-ecliptic observations of artificial satellites and some off-ecliptic data by Ulysses. In this paper, we use the solar wind speed estimated by interplanetary scintillation (IPS) observations in the whole heliosphere. Two synoptic maps of SWS estimated by IPS observations are constructed for two Carrington rotations CR 1830 and 1901; CR 1830 starting on the 11th of June, 1990 is in the maximum phase of solar activity cycle and CR 1901 starting on the 29th of September, 1995 is in the minimum phase. Each of the maps consist of 64800 (360×180) data points. Similar synoptic maps of expansion rate of the coronal magnetic field (RBR) calculated by the so-called ‘potential model’ are also constructed under a radial field assumption for CR 1830 and CR1901. Highly significant correlation (r=−0.66) is found between the SWS and the RBR during CR1901 in the solar minimum phase; that is, high-speed winds emanate from photospheric areas corresponding to low expansion rate of the coronal magnetic field and low speed winds emanate from photospheric areas of high expansion rate. A similar result is found during CR 1830 in solar maximum phase, though the correlation is relatively low (r=−0.29). The correlation is improved when both the data during CR 1830 and CR 1901 are used together; the correlation coefficient becomes −0.67 in this case. These results suggest that the correlation analysis between the SWS and the RBR can be applied to estimate the solar wind speed from the expansion rate of the coronal magnetic field, though the correlation between them may depend on the solar activity cycle. We need further study of correlation analysis for the entire solar cycle to get an accurate empirical equation for the estimation of solar wind speed. If the solar wind speed is estimated successfully by an empirical equation, it can be used as an initial condition of a solar wind model for space weather forecasts.
机译：研究太阳风速与日冕磁场扩展率之间的关系主要是通过人工卫星在黄土中的观测以及尤利西斯（Ulysses）的一些黄土外数据进行的。在本文中，我们使用通过整个太阳圈的行星际闪烁（IPS）观测值估算的太阳风速。为两次卡林顿旋转CR 1830和1901构建了两个由IPS观测估计的SWS的天气图。从1990年6月11日开始的CR 1830处于太阳活动周期的最大阶段，从1995年9月29日开始的CR 1901处于最小太阳活动周期。每个地图都包含64800（360×180）个数据点。在CR 1830和CR1901的径向场假设下，也构造了由所谓的“势能模型”计算出的类似冠状磁场（RBR）膨胀率的天气图。在太阳最小相位的CR1901期间，在SWS和RBR之间发现高度相关（r = -0.66）。即，从与冠状磁场的低膨胀率相对应的光球区域发出高速风，从高膨胀率的光球区域产生低速风。尽管相关性相对较低（r = -0.29），但在CR 1830的太阳最大相位期间也发现了类似的结果。当同时使用CR 1830和CR 1901期间的数据时，相关性得到改善。在这种情况下，相关系数变为-0.67。这些结果表明，SWS和RBR之间的相关性分析可用于根据日冕磁场的膨胀率估算太阳风速，尽管它们之间的相关性可能取决于太阳活动周期。我们需要对整个太阳周期的相关性分析进行进一步研究，以获取准确的经验公式来估算太阳风速。如果通过经验公式成功估算了太阳风速，则可以将其用作空间天气预报的太阳风模型的初始条件。

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  • 来源
    《Solar Physics》 |2002年第1期|173-185|共13页
  • 作者

    Kazuyuki Hakamada; Masayoshi Kojima; Munetoshi Tokumaru; Tomoaki Ohmi; Atsushi Yokobe; Kenichi Fujiki;

  • 作者单位

    Department of Natural Science and Mathematics Chubu University;

    Solar-Terrestrial Environment Laboratory Nagoya University;

    Solar-Terrestrial Environment Laboratory Nagoya University;

    Solar-Terrestrial Environment Laboratory Nagoya University;

    Solar-Terrestrial Environment Laboratory Nagoya University;

    Solar-Terrestrial Environment Laboratory Nagoya University;

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