Electrification life cycle of incipient thunderstorms

Autor(es)

Mattos, Enrique V. ; Machado, Luiz A. T. ; Williams, Earle R. ; Goodman, Steven J. ; Blakeslee, Richard J. ; Bailey, Jeffrey C.

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES; v. 122, n. 8, p. 4670-4697, APR 27 2017.
• Citações Web of Science: 4

Resumo

This work evaluates how clouds evolve to thunderstorms in terms of microphysical characteristics to produce the first intracloud (IC) and cloud-to-ground (CG) lightning flashes. Observations of 46 compact isolated thunderstorms during the 2011/2012 spring-summer in Southeast Brazil with an X-band polarimetric radar and two- and three-dimensional Lightning Location Systems demonstrated key parameters in a cloud's vertical structure that produce the initial electrification and lightning activity. The majority (98%) of the first CG flashes were preceded (by approximately 6min) by intracloud (IC) lightning. The most important aspect of the observations going into this paper, which came originally from the visual examination of a large number of thunderstorms, is that an initial positive differential reflectivity (Z(DR)) (associated with supercooled raindrops) evolved to reduced Z(DR) (and even negative values) in the cloud layer between 0 degrees and to -15 degrees C before and during the time of the initial lightning, suggesting evolution from supercooled raindrops to frozen particles promoting the formation of conical graupel. An enhanced negative specific differential phase (K-DP) (down to -0.5 degrees km(-1)) in the glaciated layer (above -40 degrees C) was predominantly observed at the time of the first CG flash, indicating that ice crystals, such as plates and columns, were being vertically aligned by a strong electric field. These results demonstrate that the observations of Z(DR) evolution in the mixed layer and negative K-DP in the upper levels of convective cores may provide useful information on thunderstorm vigor and lightning nowcasting. (AU)

• Processo FAPESP: 11/13673-8 - Estudos sobre a convecção profunda utilizando radar e medidas de eletricidade atmosférica durante a campanha do CHUVA - Vale do Paraíba
• Beneficiário: Luiz Augusto Toledo Machado
• Modalidade de apoio: Auxílio à Pesquisa - Pesquisador Visitante - Internacional
• Processo FAPESP: 15/14497-0 - Previsão imediata de tempestades intensas e entendimento dos processos físicos no interior das nuvens: o SOS-CHUVA (Sistema de Observação e Previsão de Tempo Severo)
• Beneficiário: Luiz Augusto Toledo Machado
• Modalidade de apoio: Auxílio à Pesquisa - Programa de Pesquisa sobre Mudanças Climáticas Globais - Temático
• Processo FAPESP: 09/15235-8 - Processos de nuvens associados aos principais sistemas precipitantes no Brasil: uma contribuição à modelagem da escala de nuvens e ao GPM (Medida Global de Precipitação)
• Beneficiário: Luiz Augusto Toledo Machado
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 11/18217-0 - O impacto da microfísica de nuvens na eletrificação de tempestades
• Beneficiário: Enrique Vieira Mattos
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 13/04292-6 - Características microfísicas das tempestades isoladas antes e durante a produção do primeiro relâmpago nuvem-solo
• Beneficiário: Enrique Vieira Mattos
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Doutorado