High-resolution simulations of the electrification and lightning in a hurricane-like vortex and in a TOGA COARE oceanic squall line.
A cloud scale model with a 12 class bulk microphysics scheme and a three-dimensional lightning parameterization was used to investigate the electrical properties of hurricane–like vortex and a well-documented tropical oceanic squall line from the Tropical Ocean Global Atmosphere Coupled Ocean Atmosphere Response Experiment (TOGA COARE) field program. This work is intended to provide a first insight on the spatial distribution of lighting and charge within such systems. The highest total lightning flash rates in the hurricane-like vortex are found primarily within the eyewall where updraft speeds tend to be larger than elsewhere in the TC, though rarely exceeding 10 ms -1 . When the model uses the Saunders and Peck non-inductive (NI) charging scheme, the charge regions involved in lightning resemble a normal tripole in the inner eyewall while a normal dipole is present in the outer eyewall stratiform region and in the strongest cells forming the outer rainbands. The charges forming the normal dipole in the outer eyewall are generated within the eyewall via NI charging near the -15℃ isotherm and later are ejected radially outward by the storm intense circulation. The simulated squall line exhibited overall weak updraft speeds and shallow echo tops resulting in a system exhibiting generally little total lightning activity. Most of the simulated flashes occurred within strong cells between the gust front and the trailing stratiform region, which exhibited a normal tripole. The main midlevel negative charge region of this tripole was attributed mainly to NI charging of low and medium density graupel and rimed cloud ice particles, while the upper positive charge region owed its existence mainly to NI charging of all three cloud ice species (rimed, columns and plates) with the remainder of the charge being deposited non-inductively on snow particles. The lowest positive charge region resulted from both inductive and non-inductive charging of medium and high density graupel.
Alexandre O. Fierro Lance M. Leslie Edward Mansell Jerry M. Straka
School of Meteorology, University of Oklahoma, Norman, Oklahoma, USA Cooperative Institute for Mesoscale Meteorological Studies (CIMMS), University of Oklahoma, and Nati
国际会议
第13届国际大气电学会议(The 13th International Conference on Atmospheric Electricity)
北京
英文
2007-08-13（万方平台首次上网日期，不代表论文的发表时间）