Fast solar wind after the rapid acceleration
Fast solar wind after the rapid acceleration
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DOI：
10.1029/2003ja010247
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发表时间：
2004-04
影响因子：
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通讯作者：
M. Kojima;A. Breen;K. Fujiki;Keiji Hayashi;T. Ohmi;M. Tokumaru
中科院分区：
文献类型：
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作者：
M. Kojima;A. Breen;K. Fujiki;Keiji Hayashi;T. Ohmi;M. Tokumaru
[1]我们研究了在0.13-0.9 AU的日心距离范围内高纬度快速太阳风速度的径向依赖性。本文提出了一种新的层析分析方法，利用行星际闪烁（IPS）观测得到了两个参考球体在0.13和0.3 AU上的速度分布图。首先，验证了该层析成像方法具有足够的灵敏度和可靠性来研究风速的径向依赖性。分析了1995 - 1997年太阳活动最小的3年IPS观测数据。在0.13 ~ 0.3 AU处的平均速度为770 ~ 780 km s−1，比在0.3 ~ 0.9 AU处的平均速度低19±17 km s−1。这项工作的结果，结合SOHO/LASCO、EISCAT和MERLIN [Breen等人，2002]、Helios [Schwenn等人，1978]和Ulysses [McComas等人，2000]的测量结果表明，在20 Rs内，快速风几乎被加速到其最终流动速度，在30 Rs以上存在一个很小但不可忽略的加速度，在更远的日心距离上，加速度趋于变小。
[1] We have studied the radial dependence of the velocity of high-latitude fast solar wind in the heliocentric distance range of 0.13–0.9 AU. For this study a new tomographic analysis method which can evaluate uncertainties was developed to obtain velocity distribution maps on two reference spheres at 0.13 and 0.3 AU using interplanetary scintillation (IPS) observations. First of all, it is tested that this tomographic method has enough sensitivity and reliability to investigate the radial dependence of the wind velocity. The analysis was made for the IPS observations during 3 years, from 1995 to 1997, when solar activity was minimum. From this analysis, average velocities of 770–780 km s−1 were obtained at distances of 0.13–0.3 AU, which were 19 ± 17 km s−1 lower than those at 0.3–0.9 AU. The results from this work, taken together with measurements of SOHO/LASCO, EISCAT and MERLIN [Breen et al., 2002], Helios [Schwenn et al., 1978], and Ulysses [McComas et al., 2000], indicate that the fast wind is accelerated almost to its final flow velocity within 20 Rs and a small but not negligible acceleration exists beyond 30 Rs which tends to become smaller at farther heliocentric distances.