A morphological study of vertical ionospheric flows in the high‐latitude F region
A morphological study of vertical ionospheric flows in the high‐latitude F region
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DOI：
10.1029/90ja02242
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发表时间：
1991-03
影响因子：
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通讯作者：
M. Loranc;W. B. Hanson;R. Heelis;J. St.‐Maurice
中科院分区：
文献类型：
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作者：
M. Loranc;W. B. Hanson;R. Heelis;J. St.‐Maurice
我们研究了DE 2卫星在200 - 1000 km高度上记录的体离子垂直漂移数据。对于这个数据集，我们发现在100 ms-1和3 km s-1之间的场向离子流在高纬度F区很常见。气流主要是向上的尖端区域附近和整个极光区。还记录到强度稍小的强向下气流，但主要是在极冠上空。这些陈述适用于所有漂移速度超过50 ms −1的情况，以及所有海拔高度和采样的磁活动水平。低空向上流动的离子的形态与在更高的高度观察到的流出离子、离子束和离子二次曲线的形态一致，但低空通量往往要大得多。这表明，大部分向上流动的离子实际上返回到电离层，作为大的向下离子通量被观察到。我们建议，上升流的离子事件产生的突然大的变化，在离子温度低于中性exobase，离子摩擦加热占主导地位的离子能量平衡。当对流场管的水平速度在尖点等区域迅速增加时，温度会发生突变。
We have studied the vertical bulk ion drift data recorded by the DE 2 satellite between 200 and 1000km altitudes. For this data set we have found that field-aligned ion flows between 100ms−1 and 3km s−1 are a common occurrence in the high-latitude F region. The flows are predominantly upward near the cusp region and throughout the auroral zone. Strong downward flows of somewhat smaller magnitude are also recorded but mostly over the polar cap. These statements are true for all drift speeds in excess of 50ms−1 and for all altitudes and magnetic activity levels sampled. The morphology of low-altitude upward flowing ions agrees well with the morphology of outflowing ions, ion beams, and ion conics observed at much higher altitudes, but the low-altitude fluxes are often considerably greater. This suggests that a large fraction of the upflowing ions actually returns to the ionosphere, to be observed as large downward ion fluxes. We propose that upflowing ion events are generated by sudden large changes in the ion temperature below the neutral exobase, where ion frictional heating dominates the ion energy balance. The sudden changes in temperature occur when the horizontal velocity of a convecting field tube increases rapidly in regions like the cusp.