Substorm dependence of chorus amplitudes: Implications for the acceleration of electrons to relativistic energies
Substorm dependence of chorus amplitudes: Implications for the acceleration of electrons to relativistic energies
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DOI：
10.1029/2000ja900156
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发表时间：
2001-07
影响因子：
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通讯作者：
N. Meredith;R. Horne;R. R. Anderson-R.
中科院分区：
文献类型：
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作者：
N. Meredith;R. Horne;R. R. Anderson-R.
目前人们对确定各种波粒相互作用在地磁暴期间/之后电子加速到相对论能量中所起的作用有着浓厚的兴趣。本文对CRRES等离子体波实验中较低波段（0.1-0.5f(ce)）和较高波段（0.5-1.0f(ce)） （f（ce）为电子回旋频率）的波数据进行了调查，以评估这些波是否在地磁暴期间和之后加速电子种子群到相对论能量方面发挥重要作用。在等离子体ause之外，合唱发射在很大程度上依赖于亚暴，当亚暴活动增强时，所有合唱发射都增强。赤道合唱（/ lambda （m) / 300 nT）的平均振幅为>0.5 mV m(-1)，主要在3 15度区域）在活动条件下在低波段最强，平均振幅为>0.5 mV m(-1)，主要在3 < L < 7区域，在白天的当地时间范围内，主要在0600-1500 MLT范围内，与磁层角的波产生一致。在安静（声发射< 100 nT）和中等（100 nT <声发射< 300 nT）条件下，在两个波段内，在夜侧的L = 4范围内，都可以看到微弱的、与亚风暴无关的平均振幅通常< 0.2 mV m（-1）。这些辐射位于等离子层内，来自闪电和地面VLF发射机的信号。我们的结论是，在亚暴期间，等离子体顶外看到的合唱振幅的显著增加支持了该区域哨声模式合唱的电子加速理论。结果表明，磁暴期间/之后的哨子模式副歌电子加速只有在磁暴主期之后有长时间的亚暴活动时才有效。
Intense interest currently exists in determining the roles played by various wave-particle interactions in the acceleration of electrons to relativistic energies during/following geomagnetic storms. Here we present a survey of wave data from the CRRES Plasma Wave Experiment for lower band (0.1-0.5f(ce)) and upper band (0.5-1.0f(ce)) chorus, f(ce) being the electron gyrofrequency, to assess whether these waves could play an important role in the acceleration of a seed population of electrons to relativistic energies during and following geomagnetic storms. Outside of the plasmapause the chorus emissions are largely substorm-dependent, and all chorus emissions are enhanced when substorm activity is enhanced. The equatorial chorus (/ lambda (m) / 300 nT) with average amplitudes typically >0.5 mV m(-1) predominantly in the region 3 15 degrees) is strongest in the lower band during active conditions, with average amplitudes typically >0.5 mV m(-1) in the region 3 < L < 7 over a range of local times on the dayside, principally in the range 0600-1500 MLT, Consistent with wave generation in the horns of the magnetosphere. An inner population of weak, substorm-independent emissions with average amplitudes generally < 0.2 mV m(-1) are seen in both bands largely inside L = 4 on the nightside during quiet (AE < 100 nT) and moderate (100 nT < AE < 300 nT) conditions. These emissions lie inside the plasmapause and are attributed to signals from lightning and ground-based VLF transmitters. We conclude that the significant increases in chorus amplitudes seen outside of the plasmapause during substorms support the theory of electron acceleration by whistler mode chorus in that region. The results suggest that electron acceleration by whistle mode chorus during/following geomagnetic storms can only be effective when there are periods of prolonged substorm activity following the main phase of the geomagnetic storm.