雷暴下的电流密度测量和准稳态特性讨论

利用电场和麦克斯韦电流密度的同时测量，对雷暴下闪电间的麦克斯韦电流密度的准稳态特性进行了验证，并利用实验观测和模式计算相结合的方法，对传导电流、位移电流和电晕电流的相对重要性作了估计。

CURRENT DENSITY MEASUREMENT BENEATH THUNDERSTORM AND ITS QUASI-STEADY FEATURES

The surface electric field E and Maxwell current density J m have been measured simultaneously under small and active thunderclouds to verify the quasi-steady characteristics of Maxwell current density. The records show that under active thunderclouds surface Maxwell current density reflects the change of cloud charge sources,and is quasi-steady between lightning discharges. Observation and model calculation show that displacement current density dominates J m when electric field near zero between lightning discharges. When electric field recovers to the value near that before the flashes and keep static value, the conduction and corona current densities increase while displacement current density decreases. Under small storms,the conduction current that flows in the atmosphere produce time variations in the Maxwell current density at the ground even if the cloud current sources is quasi-steady.