Cusp latitude and the optimal solar wind coupling function
Cusp latitude and the optimal solar wind coupling function
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DOI：
10.1029/2006ja011731
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发表时间：
2006-05
影响因子：
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通讯作者：
P. Newell;T. Sotirelis;K. Liou;C. Meng;F. Rich
中科院分区：
文献类型：
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作者：
P. Newell;T. Sotirelis;K. Liou;C. Meng;F. Rich
[1]以前的工作已经确定，低海拔粒子尖纬度与IMF的南向分量的线性相关性约为0.70。已经提出了几个可能更好的候选函数，用于确定磁层和太阳风之间的耦合，但没有一个被评估的尖点，这是一个网站的直接太阳风磁层相互作用。基于1984-1994年11年DMSP卫星粒子观测数据（并结合1995-2005年11年的验证），我们发现最佳的太阳风-磁层耦合函数涉及电场维度，如半波整流器（vBs）和Kan-Lee电场（EKL = vBTsin 2（θc/2），其中θc为IMF时钟角）。半波整流函数（r = 0.77）和Kan-Lee函数（r = 0.78）与尖点纬度的线性相关性明显优于Bz函数，也优于θ_c参数（θ_c = vB_2sin ~ 4（θ_c/2））。然而，最好的相关性是与其时钟角依赖性介于纯半波整流器（这意味着对于Bz > 0没有合并）和Kan-Lee函数之间的函数。也就是说，EWAV = vBTsin 4（θc/2）与尖点纬度在r = 0.81的水平上相关。后一种时钟角依赖性先前已经由J. R. Wygant，由S.- I. Akasofu和V.M.瓦西柳纳斯改进的结果适用于赤道和极向边缘的尖点，无论如何传播的IMF。早期的工作跨极冠电位和夜侧极光光度也有利于EWAV功能，这与我们的研究结果相结合，提出了一个广泛适用的结果。因此，昼侧合并显然不是纯粹的分量驱动，正如半波整流器公式所暗示的那样。这些结果还表明，虽然不太令人信服，合并关闭越来越北IMF更快地比Kan-Lee电场暗示。
[1] Previous work has established that the linear correlation of the low-altitude particle cusp latitude with the southward component of the IMF is about 0.70. Several possibly better candidate functions for determining the coupling between the magnetosphere and the solar wind have been advanced, but none have been evaluated in terms of the cusp, which is a site of direct solar wind–magnetosphere interaction. On the basis of 11 years of DMSP satellite particle data from 1984–1994 (with verification from the subsequent 11 years, 1995–2005), we find that the best solar wind–magnetosphere coupling function involves electric field dimensions, such as the half wave rectifier (vBs) and the Kan-Lee electric field (EKL = vBTsin2(θc/2), where θc is the IMF clock angle). Both the half wave rectifier (r = 0.77) and the Kan-Lee (r = 0.78) functions have a linear correlation with cusp latitude which is noticeably better than the Bz function used in previous work, and also better than the ɛ parameter (ɛ = vB2sin4(θc/2)). However, the best correlation is with a function whose clock angle dependence is intermediate between the pure half wave rectifier (which implies no merging for Bz > 0) and the Kan-Lee function. Namely, EWAV = vBTsin4(θc/2) correlates with cusp latitude at the r = 0.81 level. This latter clock angle dependence has been previously suggested at various times by J. R. Wygant, by S.-I. Akasofu, and by V. M. Vasyliunas. The improved result holds for both the equatorward and poleward edge of the cusp, and regardless of how the IMF is propagated. Earlier work on cross polar cap potentials and on nightside auroral luminosity also favored the EWAV function, which in combination with our findings suggests a widely applicable result. Dayside merging is thus clearly not purely component driven, as the half wave rectifier formula implies. These results also suggest, albeit less convincingly, that merging shuts down for increasingly northward IMF more rapidly than the Kan-Lee electric field implies.