Dynamic variations of a convection flow reversal in the subauroral postmidnight sector as seen by the SuperDARN Hokkaido HF radar
Dynamic variations of a convection flow reversal in the subauroral postmidnight sector as seen by the SuperDARN Hokkaido HF radar
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DOI：
10.1029/2007gl031552
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发表时间：
2007-11
影响因子：
5.2
通讯作者：
R. Kataoka;N. Nishitani;Y. Ebihara;K. Hosokawa;T. Ogawa;T. Kikuchi;Y. Miyoshi
中科院分区：
文献类型：
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作者：
R. Kataoka;N. Nishitani;Y. Ebihara;K. Hosokawa;T. Ogawa;T. Kikuchi;Y. Miyoshi
SuperDARN北海道高频雷达自2006年12月初开始连续运行，能够测量极光下电离层等离子体对流，特别是在风暴期间。本文报道了2007年1月29日风暴主阶段对午夜后亚极光扇区对流流反转动态变化的首次二维观测。气流反转区在经度20°和纬度5°以上延伸，持续时间约10 ~ 15 min，最大流速约0.5 ~ 1.0 km/s。通过环电流模拟和电离层的耦合模拟，可以合理地再现这种流反转结构，表明它是由风暴主阶段与环电流增强相关的2区场向电流产生的。流动反转结构的动态变化可以解释为细长的黄昏对流单元向午夜后和黎明对流单元赤道方向的短暂东伸，与环电流的变化有关，环电流的结构受行星际磁场和太阳风动压控制。这表明环电流的变化与行星际参数高度耦合，比以往认为的要复杂得多。
The SuperDARN Hokkaido HF radar, capable of measuring the subauroral ionospheric plasma convection especially during storms, has been in continuous operation since the beginning of December 2006. We report the first two‐dimensional observation of a dynamic variation of convection flow reversal in subauroral postmidnight sector during the storm main phase on 29 January 2007. The flow reversal region is extended over 20° in longitude and 5° in latitude, lasting for about 10–15 min, and the maximum flow speed is about 0.5–1.0 km/s. The flow reversal structure is reasonably reproduced by the ring current simulation coupled with the ionosphere, suggesting that it is produced by the region 2 field‐aligned current associated with the ring current enhancement during the storm main phase. The dynamic variation of the flow reversal structure is interpreted as a transient eastward extension of the elongated dusk convection cell to the postmidnight and equatorward of the dawn cell, associated with the variation of the ring current whose structure is controlled by the interplanetary magnetic field and solar wind dynamic pressure. It is suggested that the ring current variation is highly coupled with the interplanetary parameters and is much more complicated than ever thought.