Radiation Belt Slot Region Filling Events: Sustained Energetic Precipitation Into the Mesosphere
Radiation Belt Slot Region Filling Events: Sustained Energetic Precipitation Into the Mesosphere
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DOI：
10.1029/2018ja025890
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发表时间：
2018-09
期刊：
影响因子：
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通讯作者：
A. Kavanagh;N. Cobbett;P. Kirsch
中科院分区：
文献类型：
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作者：
A. Kavanagh;N. Cobbett;P. Kirsch
高能电子在大气中的沉降既是辐射带粒子的一种损失机制，也是地球空间环境影响地球大气的一种手段;因此，必须充分了解这种沉降的程度。一组极地轨道卫星已被用于确定高能带电粒子填充内外辐射带之间的缝隙区域的时期。这表明，能量大于30 keV的电子可以穿透该区域，即使在适度的地磁活动水平下也是如此。这些具有足够粒子通量的事件产生足够的电离，可以被南极洲的地面雷达探测到;这种降水平均持续约10天。对这些数据的分析表明，平均降水量渗透到平流层顶（约55公里高度）。对于这些事件中的一些（如果不是全部的话），最具能量的降水的可能原因是（相对论性）电子和等离子体层嘶嘶声之间的相互作用，导致降水的当地时间变化很小，如果没有的话。这并不排除纵向效应，因为所有的雷达测量都是固定的经度。在冬季，雷达处于稳定的南极大气涡旋之下。这就把大气中的物种带到了较低的高度，包括破坏臭氧的化学物质，这些化学物质是由高能降水产生的。因此，南半球槽区的降水可能会破坏臭氧，改变大气热平衡和化学;需要做更多的工作来确定这些事件的真正影响。
Precipitation of energetic electrons to the atmosphere is both a loss mechanism for radiation belt particles and a means by which the geospace environment influences the Earth's atmosphere; thus, it is important to fully understand the extent of this precipitation. A set of polar orbiting satellites have been used to identify periods when energetic charged particles fill the slot region between the inner and outer radiation belts. These suggest that electrons with energies >30 keV penetrate this region, even under levels of modest geomagnetic activity. Those events with sufficient fluxes of particles produce enough ionization to be detected by a ground‐based radar in Antarctica; this precipitation lasts for ~10 days on average. Analysis of these data reveals that the average precipitation penetrates to the stratopause (~55‐km altitude). For some (if not all) of these events, the likely cause of the most energetic precipitation is an interaction between (relativistic) electrons and plasmaspheric hiss leading to little, if no, local time variation in precipitation. This does not preclude a longitudinal effect given that all radar measurements are fixed in longitude. During winter months the radar is under the stable southern polar atmospheric vortex. This transports atmospheric species to lower altitudes including the ozone destroying chemicals that are produced by energetic precipitation. Thus, the precipitation from the slot region in the Southern Hemisphere will likely contribute to the destruction of ozone and changes to atmospheric heat balance and chemistry; more work is required to determine the true impact of these events.