EQUATORIAL SPREAD-F - IMPLICATIONS OF VHF RADAR OBSERVATIONS
EQUATORIAL SPREAD-F - IMPLICATIONS OF VHF RADAR OBSERVATIONS
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DOI：
10.1029/ja075i034p07199
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发表时间：
1970-01-01
影响因子：
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通讯作者：
MCCLURE, JP
中科院分区：
文献类型：
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作者：
FARLEY, DT;BALSLEY, BB;MCCLURE, JP
利用位于Jicamarca的强大的50 MHz雷达研究了与赤道扩展F相关的场向不规则体的散射。我们发现这些波长为3米的不规则性，首先，有时可以在F区域的任何地方产生，无论该区域以何种垂直速度移动，第二，生长时间为几秒或更短，第三，以与Flayer相当的速度移动，第四，可能达到背景热水平的107- 108倍。也有迹象表明，可能有两种类型的不规则性，大致分为强和弱，并且可能有一个最低阈值高度，在不规则性首次产生之前，Flayer的底部必须高于该高度。这些和其他观察到的不规则性的特征似乎排除了目前流行的理论，它们的起源（垂直漂移不稳定性首先提出的马丁，机制之间的E和F区域，引力不稳定性，产生的磁流体波之间的耦合，和其他）和其他几个著名的等离子体不稳定性类型。密度和漂移速度的分量仍然是不稳定性的可能来源，但目前我们只能推测最终可能被证明是正确的解释。
Scatter from field‐aligned irregularities associated with equatorial spreadFhas been studied using the powerful 50 MHz radar at Jicamarca. We find that these irregularities, which have a wavelength of 3 meters, first, at times can be generated anywhere in theFregion, no matter with what vertical velocity the region is moving, second, have growth times of a few seconds or less, third, move at velocities comparable to that of theFlayer, and fourth, may attain strengths of perhaps 107–108times the background thermal level. There are also indications that there may be two types of irregularities, classified roughly as strong and weak, and that there may be a minimum threshold altitude that the bottom of theFlayer must be above before the irregularities are first generated. These and other observed characteristics of the irregularities seem to rule out currently popular theories of their origin (the vertical drift instability suggested first by Martyn, mechanisms based on coupling between theEandFregions, gravitational instabilities, generation by hydromagnetic waves, and others) and several other well known types of plasma instability. Gradients of density and drift velocity remain as possible sources of instability, but at the moment we can only speculate as to what may ultimately prove to be the correct explanation.