首页|Transition of dominant cloud microphysical processes for increasing lightning preceding downbursts in multi-cell convective clouds
Transition of dominant cloud microphysical processes for increasing lightning preceding downbursts in multi-cell convective clouds
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NETL
NSTL
Elsevier
Based on the results of numerical simulations, a possible mechanism for the occurrence of a rapid increase in lightning frequency preceding a downburst was investigated according to cloud microphysical processes in mixed-phase areas. To elucidate the mechanism, idealized experiments were conducted targeting multi-cell convective clouds using a meteorological model coupled with a bulk lightning model, which explicitly calculates riming, charge separation via riming electrification, and lightning discharge. The model well reproduced a rapid increase in the lightning flash rate in multi-cell convective clouds approximately 15 min before a downburst. In a convective cell during increasing flash rate, solid hydrometeors were supplied to the convective area and riming electrification occurred actively. In contrast, in a convective cell that caused a downburst, riming occurred actively because of the supply of a large amount of supercooled water from the lower layers. A convective cell suitable for riming electrification or graupel growth by riming occurred when the convection was or was not tilted, respectively. The transition from tilted convection suitable for riming electrification to upright convection suitable for active riming growth is critical for the occurrence of the rapid increase of lightning preceding downbursts.
NETL
NSTL
Elsevier
