High‐latitude energy input and its impact on the thermosphere
High‐latitude energy input and its impact on the thermosphere
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DOI：
10.1002/2015ja022294
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发表时间：
2016-07
期刊：
影响因子：
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通讯作者：
G. Lu;A. Richmond;H. Lühr;L. Paxton
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文献类型：
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作者：
G. Lu;A. Richmond;H. Lühr;L. Paxton
本文通过综合2005年1月17日地磁风暴期间的各种空间和地面观测资料，对极地帽的高纬度能量输入及其分配进行了定量评估。研究发现，焦耳加热是磁层能量输入的主要形式，特别是在活动时期，半球积分焦耳加热可以比半球积分极光功率大一个数量级。大部分磁层能量耗散在极光区而不是极帽区。平均而言，只有22-25%的半球能量输入耗散到以对流逆转边界（CRB）和向极地极光通量边界（FXB）为边界的极帽区。研究了高纬度能量输入的影响，揭示了焦耳加热与极帽质量密度异常形成之间的因果关系。我们的数值模拟表明，热层动力学很容易通过上升流和大气重力波重新分配成分、温度和质量。CHAMP卫星在风暴期间观测到的极帽质量密度异常主要是大尺度大气重力波的结果。因此，局部热层质量密度的增加并不一定意味着有直接的能量输入。
This paper presents a quantitative assessment of high‐latitude energy input and its partitioning in the polar cap by synthesizing various space and ground‐based observations during the 17 January 2005 geomagnetic storm. It was found that Joule heating is the primary form of magnetospheric energy input, especially during active times when the hemispheric‐integrated Joule heating can be an order of magnitude larger than the hemispheric‐integrated auroral power. Most of magnetospheric energy is dissipated in the auroral zone rather than in the polar cap. On average, only about 22–25% of the total hemispheric energy input is dissipated into the polar cap region bordered by the convection reversal boundary (CRB) and the poleward auroral flux boundary (FXB). The impact of high‐latitude energy input was also investigated to unveil the causal relationship between Joule heating and the formation of polar cap mass density anomalies. Our numerical simulation demonstrated that thermosphere dynamics readily redistributes composition, temperature, and mass through upwelling and atmospheric gravity waves. The polar cap mass density anomalies observed by the CHAMP satellite during the storm were largely a result of large‐scale atmospheric gravity waves. Therefore, an increase in local thermospheric mass density does not necessarily mean there is direct energy input.