A high-resolution simulation of microphysics and electrification in an idealized hurricane-like vortex

Cloud-to-ground (CG) lightning bursts in the eyewall of mature tropical cyclones (TCs) are believed to be good indicators of imminent intensification of these systems. While numerous well-documented observational cases exist in the literature, no modeling studies of the electrification processes within TCs have previously been conducted. At present, little is known about the evolution of charge regions and lightning activity in mature TCs. Towards this goal, a numerical cloud model featuring a 12-class bulk microphysics scheme with electrification and lightning processes is utilized to investigate the evolution of the microphysics fields and subsequent electrical activity in an idealized hurricane-like vortex. Preliminary results show that the highest total lightning flash rates (CG plus intracloud) are primarily found within the eyewall where updraft speeds tend to be larger than elsewhere in the TC, though rarely exceeding 10ms(-1). Smaller total flash rates are also found within the strongest cells forming the outer bands, where updraft speeds sometimes reach 15ms(-1). As expected, these two regions of the storm are generally characterized by moderate total graupel mixing ratio (>= 0.5 g kg(-1)) and moderate cloud water content (>= 0.2 gm(-3)). When the model uses the Saunders and Peck non-inductive (NI) charging scheme and moderate inductive charging settings, the inner eyewall region exhibits a complex charge structure. However, the charge regions involved in lightning can be described as a normal tripole charge structure in the eyewall, while a normal dipole is observed in the outer eyewall stratiform region and in the strongest cells forming the outer rainbands. The charges forming the normaldipole in the outer eyewall are generated within the eyewall via NI charging in the mixed-phase region at mid-levels (near the -10 degrees C isotherm) and later, are ejected radially outward by the storm's intense circulation.