Effect of an MLT dependent electron loss rate on the magnetosphere-ionosphere coupling
Effect of an MLT dependent electron loss rate on the magnetosphere-ionosphere coupling
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DOI：
10.1029/2012ja018032
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发表时间：
2012-11-27
影响因子：
2.8
通讯作者：
Hsu, Tung-Shin
中科院分区：
文献类型：
--
作者：
Gkioulidou, Matina;Wang, Chih-Ping;Hsu, Tung-Shin
当等离子体薄片电子向地球漂移时，由于波粒相互作用，它们被散射到损耗锥中，由此产生的沉淀产生极光电导。因此，真实的电子损失对于模拟磁层-电离层（M-I）耦合和等离子体片电子进入内磁层的程度是重要的。为了评估电子损失的意义，我们利用耦合力平衡磁场的Rice对流模型（Rice Convection Model， RCM）模拟了不同电子损失率和自一致电场和磁场条件下的等离子体片输运。我们使用了不同大小的i)强俯仰角处处扩散的电子损失率（强率）和ii)更现实的损失率，其与波的活度有关（MLT率）。我们发现MLT速率下的电子压比L内类似12r - e的强速率下的电子压大。MLT速率下的电子沉降能量通量的黎明-黄昏不对称性，黎明比黄昏的能量通量高得多，与DMSP的统计观测结果吻合得更好。L内部类似于8r -e的高能电子在MLT速率下可以在那里停留数小时，而在强速率下的电子在几分钟内就会丢失。在MLT速率下，剩余电子在低纬度产生更高的电导；因此，在对流增强后，对流电场的屏蔽效率较低，因此，离子等离子体片比在强速率下更深地渗透到地球内部磁层。
As plasma sheet electrons drift earthward, they get scattered into the loss cone due to wave-particle interactions and the resulting precipitation produces auroral conductance. Realistic electron loss is thus important for modeling the magnetosphere - ionosphere (M-I) coupling and the degree of plasma sheet electron penetration into the inner magnetosphere. In order to evaluate the significance of electron loss, we used the Rice Convection Model (RCM) coupled with a force-balanced magnetic field to simulate plasma sheet transport under different electron loss rates and under self-consistent electric and magnetic field. We used different magnitudes of i) strong pitch angle diffusion everywhere electron loss rate (strong rate) and ii) a more realistic loss rate with its MLT dependence determined by wave activity (MLT rate). We found that electron pressure under the MLT rate is larger compared to the strong rate inside L similar to 12 R-E. The dawn-dusk asymmetry in the precipitating electron energy flux under the MLT rate, with much higher energy flux at dawn than at dusk, agrees better with statistical DMSP observations. High-energy electrons inside L similar to 8 R-E can remain there for many hours under the MLT rate, while those under the strong rate get lost within minutes. Under the MLT rate, the remaining electrons cause higher conductance at lower latitudes; thus after a convection enhancement, the shielding of the convection electric field is less efficient, and as a result, the ion plasma sheet penetrates further earthward into the inner magnetosphere than under the strong rate.