Axi-symmetric models of auroral current systems in Jupiter's magnetosphere with predictions for the Juno mission
Axi-symmetric models of auroral current systems in Jupiter's magnetosphere with predictions for the Juno mission
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DOI：
10.5194/angeo-26-4051-2008
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发表时间：
2008-12
影响因子：
1.9
通讯作者：
S. Cowley;A. Deason;E. Bunce
中科院分区：
文献类型：
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作者：
S. Cowley;A. Deason;E. Bunce
我们通过将先前在电离层高度定义的模型与磁层磁模型相结合，开发了木星系统中磁层-电离层耦合的两个相关模型，这些模型允许系统参数适当地扩展到磁层中。因此，组合模型的关键特征是它们允许在磁层观测结果（特别是由磁层-电离层耦合电流和等离子体角速度产生的方位场）与电离层极光响应之间建立直接联系。这两个模型旨在分别反映木星磁层中典型的稳态亚共转条件，以及由突然的主要太阳风引起的压缩产生的瞬态超共转条件。模型的关键简化是场、流和电流关于磁轴的轴对称性，尽管磁轴相对于行星自转轴适当倾斜并随行星旋转，但其有效性仅限于行星 30RJ 以内的径向距离。计划于 2016 年至 2017 年 NASA 新前沿朱诺号任务期间对木星极地磁层进行首次探索，主要目标是观测极地场、等离子体和紫外线发射。因此，对朱诺号规划轨道上的模型进行评估会产生可能有助于科学任务规划的预测结果。特别表明，低空近近点极地通道通常会发生在相应的极光加速区域下方，因此可以在主椭圆形的 1-3 分钟和较窄的极弧结构的 10 秒的间隔内对极光初级进行简要检查，而极光流系统在这些通道上产生的“滞后”场偏转将为 0.1，与极光电离层上方的方位角场相关。几百nT。
We develop two related models of magnetosphere- ionosphere coupling in the jovian system by combining pre- vious models defined at ionospheric heights with magneto- spheric magnetic models that allow system parameters to be extended appropriately into the magnetosphere. The key fea- ture of the combined models is thus that they allow direct connection to be made between observations in the magne- tosphere, particularly of the azimuthal field produced by the magnetosphere-ionosphere coupling currents and the plasma angular velocity, and the auroral response in the ionosphere. The two models are intended to reflect typical steady-state sub-corotation conditions in the jovian magnetosphere, and transient super-corotation produced by sudden major solar wind-induced compressions, respectively. The key simplifi- cation of the models is that of axi-symmetry of the field, flow, and currents about the magnetic axis, limiting their validity to radial distances within 30RJ of the planet, though the magnetic axis is appropriately tilted relative to the planetary spin axis and rotates with the planet. The first exploration of the jovian polar magnetosphere is planned to be undertaken in 2016-2017 during the NASA New Frontiers Juno mission, with observations of the polar field, plasma, and UV emis- sions as a major goal. Evaluation of the models along Juno planning orbits thus produces predictive results that may aid in science mission planning. It is shown in particular that the low-altitude near-periapsis polar passes will generally occur underneath the corresponding auroral acceleration regions, thus allowing brief examination of the auroral primaries over intervals of 1-3 min for the main oval and 10 s for nar- rower polar arc structures, while the "lagging" field deflec- tions produced by the auroral current systems on these passes will be 0.1 , associated with azimuthal fields above the ionosphere of a few hundred nT.