The Effect Research on Ionosphere in Response to Lightning Discharge During Thunderstorm

Large current, strong electrostatic field and radiation field generated by lightning discharges during thunderstorm activity not only cause severe natural disaster, such as oil depot explosion, forest fire and personnel casualties on the earth surface, but also exert great effects on ionosphere which leads to the perturbation of electron intensity distribution. Lightning discharge affects ionosphere in two patterns: Direct coupling and indirect coupling. The direct coupling, which shows fast very low frequency (VLF) events in VLF reflected signal, is caused by the action of quasi-electrostatic field and electro-magnetic field generated by lightning, while the indirect coupling, which exhibits lightning induced electron precipitation (LEP) in the radiation belt, is caused by the interaction between the low frequency (LF) electromagnetic wave generated by lightning and the magnetosphere during the propagation. The amplitude of LEP is related with the current of return stroke and flash rate. The lightning discharge in thunderstorm can change the distribution of electron density from D layer to F layer, and can affect the electric field between the ionosphere and troposphere. As a result, some transient glowing, such as elves and sprite can be caused. The research of transient glowing in the middle and upper atmosphere is a hot topic. The VLF reflected signal during the electro-magnetic signal propagation of lightning discharge can be used to measure the change of ionosphere density, which is a common method to detect ionosphere disturbance. The strength of ionosphere disturbance is related with lightning discharge parameters and lightning discharge types. Many results show that positive cloud-to-ground flashes, negative cloud-to-ground with large return stroke current and discharges with large transferred charge often lead to obvious ionosphere change. Nowadays, the effect research on ionosphere in response to lightning discharge often focuses on the ionosphere bottom (often called D layer), but the observation and mechanism research of the effect on ionosphere E and F layers are still limited. As for ionosphere D, the analysis is mainly based on single point observation and simulation research, and the large scale 3-D imaging of ionosphere disturbance caused by lightning discharge needs further investigation. Effect researches on ionosphere in response to lightning discharge during thunderstorm in recent years are investigated, and the direct coupling and indirect coupling between the lightning discharge and ionosphere are introduced in detail, as well as the related phenomenon caused by the interaction between lighting discharge and ionosphere.