On blanketing sporadic E and polarization effects near the equatorial electrojet
On blanketing sporadic E and polarization effects near the equatorial electrojet
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DOI：
10.1029/2008ja013158
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发表时间：
2008-09
影响因子：
--
通讯作者：
R. Tsunoda
中科院分区：
文献类型：
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作者：
R. Tsunoda
[1] 白天在赤道电喷射（EEJ）附近观察到许多令人费解的特征。它们包括 (1) 赤道带，基本上与 EEJ 并置，实际上没有覆盖零星的 E (Esb)； (2) Esb 在“禁止”带内出现，但仅当 EEJ 较弱或反转时（即反电喷射）； (3) EEJ上方偶尔出现次级电流层； (4)一次在4.3°N倾角观测到底部E层的纬度倾斜，另一次观测到出乎意料的大电子漂移速度。如果该区域的电动力学常用框架被修改为包括以下内容，这些特征将被证明是可解释的：(1) Esb 的传输由中性风中的切变控制，其中来自 EEJ 极化电场的关键贡献； (2)通过中性风和极化电场之间的动态平衡形成Esb赤道边界； (3) 由于金属离子的积累，在 Esb 边界极向的带状区域内电导率不断增加； (4)在增强的电导率带上出现二次极化电场，并且电流流过该二次电场所遍及的区域。
[1] A number of puzzling features have been observed that occur during the day in the vicinity of the equatorial electrojet (EEJ). They include (1) an equatorial belt, essentially collocated with the EEJ, that is virtually devoid of blanketing sporadic E (Esb); (2) appearances of Esb within that “forbidden” belt but only when the EEJ is weak or reversed (i.e., a counterelectrojet); (3) occasional appearances of a secondary current layer above the EEJ; and (4) observations at 4.3°N dip latitude of a latitudinal tilt in the bottomside E layer on one occasion and an unexpectedly large electron drift velocity on another. These features are shown to be accountable if the usual framework for electrodynamics in this region is modified to include the following: (1) transport of Esb that is controlled by a shear in the neutral wind with a crucial contribution from the polarization electric field of the EEJ; (2) the formation of an equatorward boundary for Esb by a dynamical balance between the neutral wind and the polarization electric field; (3) a buildup in conductivity within a band-like region, just poleward of the Esb boundary, from an accumulation of metallic ions; and (4) the appearance of a secondary polarization electric field across the band of enhanced conductivity and current flow throughout the region pervaded by that secondary electric field.