Suppression of equatorial spread F by sporadic E
Suppression of equatorial spread F by sporadic E
复制标题
零星E对赤道扩散F的抑制
DOI：
10.1029/2001ja000162
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发表时间：
2002
影响因子：
--
通讯作者：
D. Anderson
中科院分区：
文献类型：
--
作者：
A. Stephan;M. Colerico;M. Mendillo;B. Reinisch;D. Anderson
[1]我们定量地研究了低纬度、午夜前零星E层可能对赤道扩散F（ESF）的每日和每小时发展的影响。特别是，我们计算的通量管集成彼得森电导率的变化，因为它会影响瑞利-泰勒不稳定性，这决定了ESF的初始发展的增长率。我们发现，在115 ~ 120 km范围内，密度为1 × 106 cm-3的板层中，生长速率降低了一个数量级。由于黄昏后观察到的零星E层不经常达到这些值，它们不太可能是ESF日变化的来源。然而，即使是温和的增强在postsunset E区域可能会导致一个显着的抑制ESF，如果它也抑制了向上等离子体漂移的prereversal增强，赤道扩展F不稳定性的增长率的一个关键变量。因此，与不稳定性的性质一致，二阶效应（抑制向上漂移）比抑制ESF发作的一阶原因（降低F区至E区电导率）更重要。
[1] We have examined quantitatively the influence a low-latitude, premidnight sporadic E layer might have on the daily and hourly development of equatorial spread F (ESF). In particular, we calculated changes in the flux tube–integrated Pedersen conductivity as it affects the growth rate of the Rayleigh-Taylor instability, which governs the initial development of ESF. We find that the growth rate is lowered by an order of magnitude with a density of 1 × 106 cm−3 in a slab from 115 to 120 km. Since sporadic E layers observed after dusk do not regularly reach these values, they are not a likely source of the daily variability in ESF. However, even a mild enhancement in the postsunset E region could lead to a significant suppression of ESF if it also inhibits the upward plasma drift of the prereversal enhancement, a key variable in the growth rate of the equatorial spread F instability. Thus, consistent with the nature of an instability, the second-order effect (suppressed upward drift) is more important than the first-order cause (reduced F region to E region conductivity) of inhibited ESF onset.