First observation of micrometeoroid differential ablation in the atmosphere
First observation of micrometeoroid differential ablation in the atmosphere
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DOI：
10.1029/2009gl037389
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发表时间：
2009-03
影响因子：
5.2
通讯作者：
D. Janches;L. Dyrud;S. Broadley;J. Plane
中科院分区：
文献类型：
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作者：
D. Janches;L. Dyrud;S. Broadley;J. Plane
每天，数十亿微克大小的外星粒子进入地球大气层的上层并消融，将其质量沉积在中层和低层热层（MLT）中。这种蒸发的流星质量是中性金属原子的全局层、金属离子的零星E层和流星烟雾粒子的来源。由于它们的动能不足以产生可检测的光学发射，因此只能使用敏感雷达来观察这些粒子，雷达检测紧邻流星体周围的等离子体（即电子）（头部回波）或沿其路径留下的等离子体（尾迹回波）。在这里，我们表明，在流星头部回波的雷达返回信号中观察到的短尺度时间特征可以通过化学成分的差异消融来解释。这些结果代表了对这种质量损失过程的首次观察，表明这是微米级颗粒的流星质量沉积在 MLT 中的主要机制。
Every day, billions of microgram‐sized‐extraterrestrial particles enter and ablate in the upper layers of the Earth's atmosphere, depositing their mass in the mesosphere and lower thermosphere (MLT). This evaporated meteoric mass is the source of global layers of neutral metal atoms, sporadic E layers of metal ions, and meteoric smoke particles. Because their kinetic energy is insufficient to produce detectable optical emissions, these particles can only be observed using sensitive radars, which detect the plasma (i.e., electrons) either immediately surrounding the meteoroid (head‐echo), or left behind along its path (trail‐echo). Here we show that observed short‐scale temporal features in the radar returned signal from the meteor head‐echo are explained by differential ablation of the chemical constituents. These results represent the first observation of this mass‐loss process, indicating that this is the main mechanism through which the meteoric mass of micron‐sized particles is deposited in the MLT.