Electrodynamic coupling of high and low latitudes: Observations on May 27, 1993
Electrodynamic coupling of high and low latitudes: Observations on May 27, 1993
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DOI：
10.1029/2000ja000058
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发表时间：
2000-10
影响因子：
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通讯作者：
A. Kobea;A. Richmond;B. Emery;C. Peymirat;H. Lühr;T. Moretto;M. Hairston;C. Amory-Mazaudier
中科院分区：
文献类型：
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作者：
A. Kobea;A. Richmond;B. Emery;C. Peymirat;H. Lühr;T. Moretto;M. Hairston;C. Amory-Mazaudier
用1993年5月27日的地磁资料研究了从极区到地球日侧磁赤道的扰动电场的穿透情况。首先，我们研究了一个白天的赤道扰动，它伴随着从风暴中快速恢复的磁活动，具有由持续的区域2场向电流引起的过屏蔽的特征。持续了*0 3个小时。其次，我们分析了一系列周期为25-75min的起伏，以确定其振幅和相位随磁纬和磁地方时的变化。在磁赤道和极光带之间的所有纬度上，涨落都是高度相干的，但极冠的相干性降低了。中午时分赤道向北的波动伴随着中午前向南、中午前后向东和中午后向北的极光带波动。振幅从极光带向中纬度方向减小，但在赤道电急流作用下被放大。没有发现可检测到的差异，这表明对于具有这里所检查的周期的波动，可能由区域-2f对准的电流诱导的任何时间滞后都小于1min。对高纬磁场资料的天气反演分析表明，高纬东西向电位梯度的波动一般集中在中午前后，与赤道东西向电位梯度的波动是同相的。
The penetration of disturbance electric fields from the polar region to the magnetic equator on the dayside of the Earth is examined with geomagnetic data on May 27, 1993. First, we examine a dayside equatorial disturbance that followed the rapid recovery of magnetic activity from a storm and that has the characteristics of overshielding caused by persistent region-2 field-aligned currents. It lasted *0 3 hours. Second, we analyze a series of fluctuations with periods of 25-75 min, to determine the variations of amplitude and phase with magnetic latitude and magnetic local time. The fluctuations were highly coherent at all latitudes between the magnetic equator and the auroral zone, but the coherency decreasedin the polar cap. A northward fluctuation at the equator during midday hours accompanied auroral zone fluctuations that were southward before noon, eastward around noon, and northward after noon. The amplitudes decreased away from the auroral zone toward midlatitudes but were amplified under the equatorial electrojet. No detectablep hased ifferencesa re found, indicating that any temporal lags which might be inducedb y persistencein the region-2f ield-alignedc urrentsa re less than i min for fluctuations having periods like those examined here. A synoptic inversion analysis of the high-latitude magnetic data to estimate the time-varying high-latitude electric potential patterns shows that fluctuations of the high-latitude east-west potential gradient tended to be concentrated around midday, where they were in phase with fluctuations in the midday east-west potential gradient at the magnetic equator.