Evaluating stratiform cloud base charge remotely
Evaluating stratiform cloud base charge remotely
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DOI：
10.1002/2017gl073128
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发表时间：
2017-06
影响因子：
5.2
通讯作者：
R. Harrison;Keri A. Nicoll;K. L. Aplin
中科院分区：
文献类型：
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作者：
R. Harrison;Keri A. Nicoll;K. L. Aplin
层状云在其上下水平边界处由于全球电路中的垂直电流流动而获得电荷。云电荷预计会影响微物理过程，但理解是有限的，很少在现场测量。对于高度低于1公里的层状云底，云底电荷改变了下面的表面电场，从而允许一种新的远程测定方法。结合2015-2016年激光云高仪的连续云高数据和电场研磨数据，使用水平带电圆盘模型推导出云底电荷。根据43天的数据，云基电荷密度的日平均值为−0.86 nC m−2。这与云底约40米厚的均匀带电区域一致，现在证实负云底电荷是陆地层云的共同特征。这种技术也可以应用于行星大气和火山羽流。
Stratiform clouds acquire charge at their upper and lower horizontal boundaries due to vertical current flow in the global electric circuit. Cloud charge is expected to influence microphysical processes, but understanding is restricted by the infrequent in situ measurements available. For stratiform cloud bases below 1 km in altitude, the cloud base charge modifies the surface electric field beneath, allowing a new method of remote determination. Combining continuous cloud height data during 2015–2016 from a laser ceilometer with electric field mill data, cloud base charge is derived using a horizontal charged disk model. The median daily cloud base charge density found was −0.86 nC m−2 from 43 days' data. This is consistent with a uniformly charged region ~40 m thick at the cloud base, now confirming that negative cloud base charge is a common feature of terrestrial layer clouds. This technique can also be applied to planetary atmospheres and volcanic plumes.