We developed the Lightning Simulator that simulates charge distribution in thunder storm and lightning on the basis of the Cloud Resolving Storm Simulator.

Lightning activity of thunder storm has two steps. The first step is accumulationof electric charge by the cloud particles charging. The second step is discharge by lightning. In development of the lightning simulator, we newly introduced variables of charge as a prediction variable. We used the riming electrification in the first step; ice crystal, snow, and graupel that takes charge in the microphysical process. We described the formation of riming electrification and the formation of the charges. We calculated electric potential and electric field from the charge distribution . We used the lightning parametarization that uses the electric field as the threshold value of lightning initiation and parametarize discharge in the second step. We described the operation of the lightning parametarization.

Thunder strom that takes lightning on the ground in summer forms the tripole structure of the charge distribution; the positive charged particle region in upper layer, the negativey charged particle region in middle layer, and the small positivey charged particle region in lower layer. We performed ideal 2D experiment in order to examine reproducibility of tripole structure of the charge distribution within the riming electrification and the lightning parametarization. The horizontal resolution is 500m and artifactual sounding data is used as initial field. As a result, thunder strom that took the cloud-ground discharges and the cloud flashs in the model formed the tripole structure of the charge distribution.

Next, we performed 3D experiment of the thunder storm developed over Aichi prefecture of Japan on 12 August 2006. We compared the lightning strike point in the model with lightning strike point observed by Lightning Location System operated by Chubu Electric Power Co.,Inc. The horizontal resolution is 4km and realistic environment data is used as initial field. As a result, in the model the timing and area was not exactly simulated, but generated thunder storm took the lightning on Aichi prefecture. In this experiment, the lightning model could simulate the thunder strom that takes the lightning on the ground.