Fully adiabatic changes in storm time relativistic electron fluxes
Fully adiabatic changes in storm time relativistic electron fluxes
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DOI：
10.1029/97ja01814
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发表时间：
1997-10-01
影响因子：
2.8
通讯作者：
Chan, AA
中科院分区：
文献类型：
--
作者：
Kim, HJ;Chan, AA
有人认为，地球同步轨道上风暴时间相对论电子通量的下降和随后的恢复可以用对磁场变化的完全绝热响应（所有三个绝热不变量守恒）来解释。为了计算这种影响，我们假设一个prestorm电子通量分布构造从CRRES卫星数据，我们使用模块化磁层磁场模型来表示的磁场配置之前和期间的风暴，我们使用刘维尔定理来发展的prestorm电子通量。在这项工作中，我们专注于赤道镜像电子的重要特殊情况。在Dst最小值为-100 nT的风暴的主相期间，我们发现完全绝热效应可以导致高达2个数量级的通量减少，与观测到的通量减少一致。我们还发现，完全绝热通量减少的幅度较大的较低的能量，再次与观察。由于黎明侧磁层顶的损失，预计磁暴前电子通量对同步轨道恢复阶段通量增加的贡献很小。1993年11月2日至5日，风暴完全绝热通量与测量的电子通量的比较表明，对于这个事件的完全绝热效应可能有助于观察到的减少，但非绝热效应显然是重要的。总体而言，我们的结论是，完全绝热效应可以占一个显着的分数所观察到的通量减少，所观察到的和完全绝热通量之间的差异有助于澄清何时何地存在额外的损失和源机制。
It has been suggested that much of the drop and subsequent recovery of storm time relativistic electron fluxes at geosynchronous orbit can be explained in terms of a fully adiabatic response (all three adiabatic invariants conserved) to magnetic field changes. To calculate this effect, we assume a prestorm electron flux distribution constructed from CRRES satellite data, we use modular magnetospheric magnetic field models to represent the magnetic field configuration before and during the storm, and we use Liouville's theorem to evolve the prestorm electron flux. In this work we focus on the important special case of equatorially mirroring electrons. During the main phase of a storm with a Dst minimum of -100 nT we find that the fully adiabatic effect can cause a flux decrease of up to 2 orders of magnitude, consistent with observed flux decreases. We also find that the magnitude of the fully adiabatic flux decrease is larger for lower energies, again in agreement with observations. The contribution of prestorm electron fluxes to the recovery phase flux increase at synchronous orbit is expected to be small because of losses to the dawnside magnetopause. A comparison of fully adiabatic fluxes with measured electron fluxes for the November 2-5, 1993, storm indicates that for this event the fully adiabatic effect may be contributing to the observed decrease but that nonadiabatic effects are clearly important. Overall we conclude that the fully adiabatic effect can account for a significant fraction of observed flux decreases and that differences between the observed and the fully adiabatic fluxes help to clarify when and where additional loss and source mechanisms exist.