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首页> 外文期刊>Journal of Geophysical Research, A. Space Physics: JGR >Solar wind driving and substorm triggering
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Solar wind driving and substorm triggering

机译：太阳风驾驶和亚暴触发

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We compare solar wind driving and its changes for three data sets: (1) 4861 identifications of substorm onsets from satellite global imagers (Polar UVI and IMAGE FUV); (2) a similar number of otherwise random times chosen with a similar solar wind distribution (slightly elevated driving); (3) completely random times. Multiple measures of solar wind driving were used, including interplanetary magnetic field (IMF) B,, the Kan-Lee electric field, the Borovsky function, and dcl'mpldt (all of which estimate dayside merging). Superposed epoch analysis verifies that the mean B, has a northward turning (or at least averages less southward) starting 20 min before onset. We argue that the delay between IMF impact on the magnetopause and tail effects appearing in the ionosphere is about that long. The northward turning is not the effect of a few extreme events. The median field shows the same result, as do all other measures of solar wind driving. We compare the rate of northward turning to that observed after random times with slightly elevated driving. The subsequent reversion to mean is essentially the same between random elevations and substorms. To further verify this, we consider in detail the distribution of changes from the statistical peak (20 min prior to onset) to onset. For Bz, the mean change after onset is +0.14 nT (i.e., IMF becomes more northward), but the standard deviation is a- = 2.8 nT. Thus large changes in either direction are common. For Ems,, the change is –15 nT km/s ± 830 nT km/s. Thus either a hypothesis predicting northward turnings or one predicting southward turnings would find abundant yet random confirming examples. Indeed, applying the Lyons et al. (1997) trigger criteria (excluding only the prior requirement of 22/30 min B_z < 0, which is often not valid for actual substorms) to these three sets of data shows that "northward turning triggers" occur in 23% of the random data, 24% of the actual substorms, and after 27% of the random elevations. These results strongly support the idea of Morley and Freeman (2007), that substorms require initial elevated solar wind driving, but that there is no evidence for external triggering. Finally dynamic pressure, p, and velocity, v, show no meaningful variation around onset (although p averages 10% above an 11 year mean).
机译：我们比较太阳风驾驶和它的变化三个数据集:(1)4861年的识别亚暴发作从全球卫星成像系统(极紫外线指数和图像FUV);否则随机次类似的选择太阳风分布(稍微偏高驾驶);太阳风驾驶的措施被使用,包括行星际磁场(IMF) B,,Borovsky Kan-Lee电场函数,和dcl 'mpldt(所有的估计的光面合并)。验证的意思是B,向北转弯开始向南(或者至少平均少)20分钟之前开始。国际货币基金组织(IMF)对磁层和尾效应的影响出现在电离层是那么久。向北转不几的影响极端事件。因此,所有其他措施的太阳风开车。与略随机时间后观察高架开车。意思是随机之间本质上是相同的海拔和亚暴的。我们详细考虑的分布变化从统计的峰值(20分钟前开始)发病。+ 0.14元(即,国际货币基金组织(IMF)变得更向北),但是标准差是a - = 2.8元。因此大两个方向的变化是常见的。《change是人——15 nT km / s±830 nT km / s。一个假说预测向北转向向南或一个预测切屑会发现丰富的随机确定的例子。应用里昂et al。(1997)触发条件(不包括只有之前要求的22/30分钟说是< 0,这通常不是实际有效亚暴的)这三组数据显示“向北将触发”发生在23%的随机数据,实际为亚暴的24%后随机海拔高度的27%。强烈支持莫雷和弗里曼的想法(2007),亚暴的需要最初的升高太阳风开车,但没有证据外部的触发。压力,p,和速度,v,没有意义变化在发生(尽管p平均值10%11年以上的意思)。

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