High spatial and temporal resolution observations of an impulse-driven field line resonance in radar backscatter artificially generated with the Tromsø heater
High spatial and temporal resolution observations of an impulse-driven field line resonance in radar backscatter artificially generated with the Tromsø heater
复制标题
使用特罗姆瑟加热器人工产生的雷达反向散射中的脉冲驱动场线共振的高空间和时间分辨率观测
DOI：
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
M. Rietveld
中科院分区：
文献类型：
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作者：
T. Yeoman;D. Wright;T. Robinson;J. Davies;M. Rietveld
CUTLASS芬兰高频雷达与EISCAT特罗姆什特罗射频电离层加热器设施一起运行，以检查磁层脉冲引起的空腔模式驱动的场线共振发展的ULF波特征。当加热器打开时，电离层的电子密度不规则性会产生场对齐的条纹，产生一个足够大的雷达目标，允许仅在1秒内进行后积分。当与15公里距离门相结合时，这使得雷达测量自然发生的ULF波的时间和空间分辨率比以前更好。的ULF波的时间相关的签名已被检查，因为它从一个大规模的腔共振，通过一个瞬态的波周期是纬度相关的和振荡的特点，自由振铃场线，最后一个非常狭窄的，小规模的局部场线共振的演变。FLR的共振宽度仅为60 km，这与以前的观测和理论相比。FLR波特征在地面磁力计数据中强烈衰减。脉冲驱动的FLR的特性只能用地面磁力计数据粗略地获得，事实上，准确确定腔和场线谐振系统的特性挑战了目前电离层雷达技术的局限性。最新的电离层雷达与诸如特罗姆什电离层加热器等设施相结合，可成为地球物理研究的一个强有力的新工具。
The CUTLASS Finland HF radar has been operated in conjunction with the EISCAT Tromsø RF ionospheric heater facility to examine a ULF wave characteristic of the development of a field line resonance (FLR) driven by a cavity mode caused by a magnetospheric impulse. When the heater is on, striating the ionosphere with field-aligned ionospheric electron density irregularities, a large enough radar target is generated to allow post-integration over only 1 second. When combined with 15 km range gates, this gives radar measurements of a naturally occurring ULF wave at a far better temporal and spatial resolution than has been achieved previously. The time-dependent signature of the ULF wave has been examined as it evolves from a large-scale cavity resonance, through a transient where the wave period was latitude-dependent and the oscillation had the characteristics of freely ringing field lines, and finally to a very narrow, small-scale local field line resonance. The resonance width of the FLR is only 60 km and this is compared with previous observations and theory. The FLR wave signature is strongly attenuated in the ground magnetometer data. The characterisation of the impulse driven FLR was only achieved very crudely with the ground magnetometer data and, in fact, an accurate determination of the properties of the cavity and field line resonant systems challenges the currently available limitations of ionospheric radar techniques. The combination of the latest ionospheric radars and facilities such as the Tromsø ionospheric heater can result in a powerful new tool for geophysical research.