Effects of positive corona on upward leader initiation from tall building by 3D numerical simulation

The initiation of the stable upward leader (SUL) is an important criterion to judge whether a building can be struck by lightning. The corona layer above the tip of a building caused by thunderstorm will affect upward leader initiation; however, there are few studies on the degree of its specific impact. Therefore, based on the established three-dimensional corona discharge model (Guo et al., 2022) and the dynamic critical length criterion of initial streamer as reported by Guo et al. (2020), we establish an SUL initiation model with corona discharge at the tip of the tall building. It is found that the simulated results of our model (considering corona discharge) match well with actual observations. The model is then used to simulate buildings with different height and different peak current of lightning strike (IP). The effect of positive corona discharge at the tip of the building on the initiation of the positive SUL during downward negative cloud-to-ground flash is discussed. The results show the following: 1) for certain IP values, the effect of corona discharge at the tip of the building has a greater effect on taller buildings than shorter ones. 2) For buildings of the same height, as Ip decreases, the effect of corona discharge at the tip of the building becomes greater. For example, for an IP of 20 kA and an Hb of 200 m, at the moment of the SUL initiated from the building, the height of the DL tip above the ground is 550 m when the corona layer is considered in the simulation and is 861 m when which is not considered. The difference between them have reached at 36%.