Auroral electrojets variations caused by recurrent high-speed solar wind streams during the extreme solar minimum of 2008
Auroral electrojets variations caused by recurrent high-speed solar wind streams during the extreme solar minimum of 2008
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DOI：
10.1029/2011ja017458
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发表时间：
2012-04
影响因子：
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通讯作者：
Jianpeng Guo;Xueshang Feng;T. Pulkkinen;E. Tanskanen;Wen-yao Xu;J. Lei;B. Emery
中科院分区：
文献类型：
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作者：
Jianpeng Guo;Xueshang Feng;T. Pulkkinen;E. Tanskanen;Wen-yao Xu;J. Lei;B. Emery
利用IMAGE网络的地磁观测资料研究了2008年极端太阳活动极小期极光电急流对周期性高速太阳风流的响应。我们首先将全球Au/AL指数与从IMAGE磁力计链确定的相应IU/IL指数进行比较，发现本地IMAGE链可以更好地监测2008年期间MLT扇区1230-2230中IU和2230-0630中IL的活动。在最佳MLT扇区，东向和向西向的电急流及其中心纬度揭示了与经常性HSS相关的明显的9天周期变化。对于9天扰动，东向和向西向的电急流与平行电场（EPAR）和电子半球功率（HPe）的相关性比与其他强迫参数更好。有趣的是，向东的电喷射仅在其最佳MLT扇区的一部分（大约1200-1800）中与EPAR和HPe表现出良好的相关性（r > 0.6），而向西的电喷射在其整个最佳MLT扇区中与EPAR和HPe表现出良好的相关性（r < -0.6）。在MLT 1800-2200扇区，东向电急流与EPAR和HPe之间的相关性较差，这可能是由于其他磁层-电离层耦合过程的影响。东向和向西电急流对EPAR的灵敏度分别接近0.06 MA/（mV/m）和-0.12 MA/（mV/m），其中心纬度对EPAR的灵敏度分别接近-2.83 Deg/（mV/m）和-2.14 Deg/（mV/m）。观测到的极光电喷流对太阳风强迫的响应为研究控制向西极光电喷流的物理过程提供了新的机会。
The IMAGE network magnetic measurements are used to investigate the response of the auroral electrojets to the recurrent high-speed solar wind streams (HSSs) during the extreme solar minimum period of 2008. We first compare the global AU/AL indices with the corresponding IU/IL indices determined from the IMAGE magnetometer chain and find that the local IMAGE chain can better monitor the activity in MLT sectors 1230-2230 for IU and 2230-0630 for IL during 2008. In the optimal MLT sectors, the eastward and westward electrojets and their central latitude reveal clear 9-day periodic variations associated with the recurrent HSSs. For the 9-day perturbations, both the eastward and westward electrojet currents are better correlated with parallel electric field (EPAR) and electron hemispheric power (HPe) than with other forcing parameters. Interestingly, the eastward electrojet shows good correlations (r > 0.6) with EPAR and HPe only in part of its optimal MLT-sector, roughly 1200-1800, while the westward electrojet shows good correlations (r < -0.6) with EPAR and HPe in its whole optimal MLT sector. The poor correlations between the eastward electrojet and EPAR and HPe in the MLT sector 1800-2200 might be attributed to the impact of other magnetosphere-ionosphere coupling processes. The sensitivities of the eastward and westward electrojet currents to EPAR are close to 0.06 MA/(mV/m) and -0.12 MA/(mV/m), respectively, and the sensitivities of their central latitudes to EPAR are close to -2.83 Deg/(mV/m) and -2.14 Deg/(mV/m), respectively. The observed auroral electrojet response to the recurrent solar wind forcing provides new opportunities to study the physical processes governing the eastward and westward auroral electrojets.