Ionospheric footprint of magnetosheathlike particle precipitation observed by an incoherent scatter radar. (Reannouncement with new availability information). Technical report
Ionospheric footprint of magnetosheathlike particle precipitation observed by an incoherent scatter radar. (Reannouncement with new availability information). Technical report
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非相干散射雷达观测到的磁鞘状粒子降水的电离层足迹。
DOI：
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发表时间：
1994
期刊：
影响因子：
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通讯作者：
F. Rich
中科院分区：
文献类型：
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作者：
J. Watermann;D. Lummerzheim;O. Beaujardiere;P. Newell;F. Rich
作者研究了Sondrestrom非相干散射雷达对电离层等离子体密度和温度分布的观测，以及对DMSP-F7卫星在前夜通过雷达视场时F区离子漂移的测量。航天器穿越了特征能量低于约200 eV的强烈电子沉淀区。具有如此低特征能量的粒子被认为直接或间接起源于磁鞘。降水区的宽度约为2°不变纬度，覆盖了低纬边界层(LLBL)、尖点和等离子体地幔(PM)的赤道方向部分。在DMSP-F7探测到软电子通量的不变纬度范围内，共转雷达在当地时间约10.5至12磁时之间的F2区观测到一块电子密度增强和电子温度升高的斑块。同样由雷达获得的离子漂移图案表明，等离子体斑块不太可能是由太阳辐射产生并平流到雷达视野中的。作者认为，雷达观测到的电离层等离子体分布发生了变化，这是由于磁鞘电子直接进入磁层并向下进入电离层高度造成的。更多关于电离层对观测到的电子沉淀的响应的模型计算支持这一解释。在这种情况下，PM的LLBL、尖点和赤道方向部分的电子通量的光谱特征太相似了，不能仅用非相干散射雷达测量来区分它们。
The authors have examined Sondrestrom incoherent scatter radar observations of ionospheric plasma density and temperature distributions and measurements of F region ion drifts that were made during a prenoon pass of the DMSP-F7 satellite through the radar field of view. The spacecraft traversed a region of intense electron precipitation with a characteristic energy below approximately 200 eV. Particles with such low characteristic energies are believed to be directly or indirectly of magnetosheath origin. The precipitation region had a width of about 2 deg invariant latitude and covered the low-latitude boundary layer (LLBL), the cusp, and the equatorward section of the plasma mantle (PM). The corotating radar observed a patch of enhanced electron density and elevated electron temperature in the F2 region between about 10.5 and 12 magnetic local time in the same invariant latitude range where DMSP-F7 detected the soft-electron flux. The ion drift pattern, also obtained by radar, shows that it is unlikely that the plasma patch was produced by solar radiation and advected into the radar field of view. The authors suggest that the radar observed modifications of the ionospheric plasma distribution, which resulted from direct entry of magnetosheath electrons into the magnetosphere and down to ionospheric altitudes.more » Model calculations of the ionospheric response to the observed electron precipitation support this interpretation. The spectral characteristics of the electron flux in the LLBL, cusp, and equatorward section of the PM were in this case too similar to allow to distinguish between them by using incoherent scatter radar measurements only.« less