HF radar polar patch and its relation with the cusp during BY‐dominated IMF: Simultaneous observations at two altitudes
HF radar polar patch and its relation with the cusp during BY‐dominated IMF: Simultaneous observations at two altitudes
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DOI：
10.1029/2008ja013624
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发表时间：
2009-02
影响因子：
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通讯作者：
S. Taguchi;K. Hosokawa;A. Nakao;M. Collier;T. Moore;N. Sato;A. Yukimatu
中科院分区：
文献类型：
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作者：
S. Taguchi;K. Hosokawa;A. Nakao;M. Collier;T. Moore;N. Sato;A. Yukimatu
[1]最近的研究表明，尖点的运动可以从IMAGE航天器上的低能中性原子成像仪在磁层中探测到的高能中性原子信号中推断出来。我们使用这种方法来了解在向阳面电离层中看到的极补丁的形成的特性。在2001年3月28日LENA尖点信号事件期间，位于Syowa East、Syowa South和Kerguelen Island的SuperDARN雷达发现了极地斑块的大尺度特征。雷达观测到的高后向散射功率区在77 °附近分成两部分，高纬部分向极方向和黄昏方向移动。分离纬度比从LENA尖点信号推断出的尖点的赤道边界高约5 °。我们解释这些观测结果，包括与其他SuperDARN雷达在北方半球获得的功能，是由于国际货币基金组织的BY控制的纬向急流，发生在一段时间内的增加，在BZ/BZ的，而不需要改变的极性，已在以前的研究中经常调用。极地斑块雷达信号的明显的赤道边界将是通常在反太阳方向的预先存在的气流和增强的纬向气流之间的界面。流动增强似乎是一个基本的过程，形成大规模的极地补丁在纬度几个度以上的尖点。
[1] Recent studies have shown that the motion of the cusp can be deduced from the energetic neutral atom signals detected in the magnetosphere by the Low Energy Neutral Atom (LENA) imager on the IMAGE spacecraft. We use this approach to understand the characteristics of the formation of a polar patch seen in the dayside ionosphere. During a period of the 28 March 2001 LENA cusp signal event, the SuperDARN radars at Syowa East, Syowa South, and Kerguelen Island identified large-scale features of a polar patch. A region of high backscatter power observed by the radars separates into two parts around 77°, and its high-latitude part moves in the poleward and duskward direction. The separation latitude is about 5° higher than the equatorward boundary of the cusp, which is deduced from the LENA cusp signal. We interpret these observations, including features obtained with other SuperDARN radars in the northern hemisphere, as being due to the IMF BY-controlled zonal jet flow that occurred during a period of increase in ∣BY/BZ∣, without requiring the change in BY polarity that has been often invoked in previous studies. The sharp equatorward boundary of the radar signatures of the polar patch would be an interface between the preexisting flow generally in the antisunward direction and the enhanced zonal flow. The flow enhancement appears to be a fundamental process that forms the large-scale polar patch at latitudes several degrees higher than the cusp.