Numerical Simulation Of The Relationship Of The Lightning Discharge With The Space Charge And Potential Distribution In Thundercloud

In this paper, we have presented the 2-dimensional (2D) and 3-dimensional (3D) Thunderstorm Electrification and Lightning Model (TELM) which incorporated the Bi-directional Stochastic Lightning Parameterization (BSLP) scheme and electrification scheme with both non-inductive and inductive charge separation into the cumulus model developed by the Chinese Academy of Meteorological Sciences. Then we have verified the TELM, investigated the differences of simulation results between coarse and fine resolution BSLP, and discussed the relationship of the channel structure and propagation features of intracloud (IC), cloud-to-ground (CG) flash with thundercloud space charge and electric potential distributions from 2D fine resolution (12.5 m) simulations. Finally we presented the similarities and differences of simulation results between 2D and 3D model in terms of the coarse resolution (500 m) simulations within 3D domain. Some new results from the simulations are as follows:1 Proved that the lightning channel structures from fine resolution simulation within 2D domain are consistent with observation data and it is necessary for research of lightning physics to perform fine resolution simulation.(1) Under charge distribution background obtained from 2D TELM within 250 space resolution, we simulated IC and CG discharges in 12.5 m resolution by using BSLP scheme. Simulation results indicate that the bi-level branched channel structure, horizontal extending ranges and maximum vertical electric field changes are in good agreement with the corresponding observed data. The positive and negative CG flashes have been simulated which downward leaders initiated inside thundercloud and struck the ground. The propagation behavior of upward and downward leaders is consistent with that observed by VHF location techniques.(2) Under coarse resolution, the lateral extension for both positive and negative leaders is very limited. There is no obvious lateral branching, and the bi-level channel structure is indiscernible. It is difficult for simulated lighting within coarse resolution to propagate in low-density charge regions. Moreover, electrostatic energies can't be consumed adequately by single lightning event from coarse simulations, which result in the more flash frequencies than those of the actual thunderstorms. This can be readily explained by the fact that coarse resolution simulations not only reduce the potential gradient between lightning channels and...