Effects of Transequatorial Thermospheric Wind on Plasma Bubble Occurrences
Effects of Transequatorial Thermospheric Wind on Plasma Bubble Occurrences
复制标题
跨赤道热层风对等离子体气泡发生的影响
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
Maruyama Takashi
中科院分区：
文献类型：
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作者：
Saito Susumu;Maruyama Takashi
等离子体泡是低纬度的赤道地磁现象，在电离层探测仪观测中表现为强烈的距离型扩展F（赤道扩展F或ESF）。术语“距离型扩展F”是指F区回波在整个频带上的模糊痕迹，可能是由于电离层不规则性的各种尺度引起的电离层探测无线电波的散射造成的。目前，等离子体泡的物理机制是等离子体中的瑞利-泰勒不稳定性。当电离层被强烈的电离层电场向东向日落方向移动时，等离子体泡就会形成，这就是所谓的“反转前增强（PRE）”。然而，PRE的强度和等离子体气泡的形成之间并不总是存在明确的对应关系[1]，即使在存在强PRE的情况下，也可能形成或不形成等离子体气泡。等离子体气泡发生的日常变化是显着的，因此等离子体气泡形成的频率是众所周知的，取决于季节，经度，太阳活动和其他因素，但仍然留下一些进一步澄清的空间。到目前为止，已经提出了各种物理机制，支配PRE的强度和等离子体气泡的形成之间的关系，但还没有产生一个明确的解决方案。Maruyama和Matuura[2]使用基于卫星的顶侧探测（卫星电离层探测仪）数据进行了分析，发现ESF发生的季节和纵向变化与等离子体密度的纬度分布的几何形状密切相关，并且当等离子体密度相对于磁纬度具有对称的纬度分布时，ESF经常被观测到。他们认为南北不对称
Plasma bubbles are low-latitude, equatorial geomagnetic phenomena that in an ionosonde observation appear as intense range-type spread F (equatorial spread F or ESF). The term “range-type spread F” refers to an obscure appearance of traces of F-region echoes across an entire frequency band, possibly caused by a scattering of ionosonde radio waves due to various scales of ionospheric irregularities. Today, the physical mechanism of plasma bubbles is the Rayleigh-Taylor instability in plasmas. Plasma bubbles are known to form when the ionospheric is significantly uplifted by an intense ionospheric electric field moving eastward towards the sunset in what is known as “prereversal enhancement (PRE).” However, a definite correspondence between the intensity of PRE and the formation of plasma bubbles does not always exist[1], and a plasma bubble may or may not form even where intense PRE is present. Day-to-day variations of plasma bubble occurrence are significantly marked so that the frequency of plasma bubbles forming is well-known to depend on the season, longitude, solar activity and other factors, but still leave some room for further clarification. Various physical mechanisms that dominate the relation between the intensity of PRE and the formation of plasma bubbles have been suggested to date, but none has yet to yield a definite solution. Maruyama and Matuura[2] conducted analyses using satellite-based topside sounding (satellite-borne ionosonde) data and found that seasonal and longitudinal changes in ESF occurrence have a close bearing on the geometry of latitude distributions of plasma density, and that ESF is frequently observed when plasma density has symmetric latitude distributions with respect to the magnetic latitude. They thought that the north-south asymmetry