HR: 1340h AN: AE33B-0308 TI: Terrestrial Gamma-ray Flash Production by Lightning Current Pulses AU: Carlson, B E EM: brantc@stanford.edu AF: Physics, Stanford University, Stanford, CA, United States AU: Lehtinen, N G EM: nleht@stanford.edu AF: Electrical Engineering, Stanford University, Stanford, CA, United States AU: Inan, U S EM: inan@stanford.edu AF: Electrical Engineering, Stanford University, Stanford, CA, United States AB: Terrestrial gamma-ray flashes (TGFs) seem to originate from cloud altitudes, requiring very large initial populations of relativistic electrons to produce sufficiently intense gamma-ray emissions. Such TGF production in the vicinity of lightning has led to the suggestion that large runaway electron populations may be produced directly by cold runaway in the lightning leader itself. We present initial results of a method of moments model of the time-dependent electric field near lightning leaders, the runaway relativistic electron avalanches driven by such fields, and the photon emissions that result. Current pulses along leader channels drive leader activity and act to intensify the local fields, suggesting a lightning current pulse TGF production mechanism consistent with existing TGF observations. We give constraints on the source lightning and leader activity necessary to produce photon emissions consistent with TGF observations, and discuss the role of relativistic feedback. DE: [0644] ELECTROMAGNETICS / Numerical methods DE: [3304] ATMOSPHERIC PROCESSES / Atmospheric electricity DE: [3324] ATMOSPHERIC PROCESSES / Lightning SC: Atmospheric and Space Electricity (AE) MN: 2009 Fall Meeting