| 1. Identificação | |
| Tipo de Referência | Artigo em Evento (Conference Proceedings) |
| Site | mtc-m16d.sid.inpe.br |
| Código do Detentor | isadg {BR SPINPE} ibi 8JMKD3MGPCW/3DT298S |
| Identificador | 8JMKD3MGP7W/383BFTB |
| Repositório | sid.inpe.br/mtc-m19@80/2010/08.10.19.18 |
| Última Atualização | 2015:03.27.18.26.26 (UTC) administrator |
| Repositório de Metadados | sid.inpe.br/mtc-m19@80/2010/08.10.19.18.25 |
| Última Atualização dos Metadados | 2018:06.05.04.37.16 (UTC) administrator |
| Chave Secundária | INPE--PRE/ |
| Chave de Citação | CamposSaWaCuKrOr:2010:DoAvDo |
| Título | Does the average downward speed of a lightning leader change as it approaches the ground? An observational approach  |
| Ano | 2010 |
| Data de Acesso | 11 maio 2024 |
| Tipo Secundário | PRE CI |
| Número de Arquivos | 1 |
| Tamanho | 430 KiB |
| 2. Contextualização | |
| Autor | 1 Campos, Leandro Zanella de Souza 2 Saba, Marcelo Magalhães Fares 3 Warner, T. A 4 Cummins, K. L 5 Krider, E. Philip 6 Orville, R. E |
| Grupo | 1 DGE-CEA-INPE-MCT-BR 2 DGE-CEA-INPE-MCT-BR |
| Afiliação | 1 Instituto Nacional de Pesquisas Espaciais (INPE) 2 Instituto Nacional de Pesquisas Espaciais (INPE) 3 South Dakota School of Mines and Technology 4 University of Arizona 5 University of Arizona 6 Texas A&M University |
| Endereço de e-Mail do Autor | 1 leandro.zanella@gmail.com 2 marcelo.saba@inpe.br |
| Endereço de e-Mail | alessandra@sid.inpe.br |
| Nome do Evento | International Lightning Detection Conference, 21. |
| Localização do Evento | Orlando |
| Data | 19 - 20 Apr. |
| Título do Livro | Proceedings |
| Histórico (UTC) | 2011-01-04 13:02:29 :: alessandra@sid.inpe.br -> administrator :: 2010 2018-06-05 04:37:16 :: administrator -> simone :: 2010 |
| 3. Conteúdo e estrutura | |
| É a matriz ou uma cópia? | é a matriz |
| Estágio do Conteúdo | concluido |
| Transferível | 1 |
| Tipo do Conteúdo | External Contribution |
| Tipo de Versão | publisher |
| Palavras-Chave | Lightning Physics Atmospheric Electricity High-speed video observations Stepped-leader velocities Positive leaders Positive lightning |
| Resumo | In the lightning literature, it is commonly assumed that the stepped-leaders that initiate the first return stroke in negative cloud-to-ground lightning flashes accelerate during the final stages of their development, but there have been only a few observational studies supporting this claim. Other studies have reported a tendency for positive leaders to accelerate and negative dart-leaders to decelerate. The aim of this investigation is to determine how the average two-dimensional (2-D) downward speed of lightning leaders changes as they approach the ground and to see if any such changes depend on the leader type, polarity, or instrumentation used to measure the speed. We have examined the optical properties of leaders that were recorded using high-speed video cameras at different sites in south and southeastern Brazil, southern Arizona, and South Dakota, in conjunction with data obtained by lightning locating systems. The GPS time-stamped cameras were operated at frame rates ranging from 1000 to 11,854 frames per second. Our dataset consisted of 46 negative steppedleaders, 53 negative dart-leaders, and 28 positive leaders. Two different approaches were used in the data analysis; first, the average downward speed of individual leaders was computed over preset distance intervals above the ground, i.e. from 0 to 500 m, 500 to 1000 m, etc, and then the geometric mean (GM) was calculated for all the cases in a given interval. We computed and compared the GMs since the speeds of positive leaders and negative dart-leaders follow a lognormal distribution (at the 0.05 level, according to the Shapiro-Wilk test), and the negative stepped-leaders have a similar distribution (according to the Kolmogorov-Smirnov test). The GM of the positive leader speeds increases by about a factor of 10 as they get closer to the ground (i.e. from 104 to 105 m/s), and the GM speed of negative stepped-leaders varies between 2.5x105 and 3.0x105 m/s. On the other hand, the GM speed of negative dart-leaders shows a clear decrease as they approach the ground. The second approach involved analyzing the leaders individually over their measurable length, and we found that: a) 82% of the 20 positive leaders accelerated, 7% decelerated, and 11% oscillated around an average speed; b) 46% of the 46 negative stepped-leaders accelerated, 6% decelerated and 48% oscillated around an average speed; and c) 32.1% of the 53 negative dart-leaders accelerated, 54.7% decelerated, and 13.2% oscillated around an average speed. We conclude that the acceleration of negative stepped-leaders is not as strong as some authors have assumed, but the tendencies for positive leaders to accelerate and for negative dart-leaders to decelerate are clear and agree with previous studies. We believe that the presented behavior asymmetry between negative stepped- and positive leaders might suggest microphysical differences in their propagation which should be investigated further. |
| Área | CEA |
| Arranjo | urlib.net > BDMCI > Fonds > Produção anterior à 2021 > DIDGE > Does the average... |
| Conteúdo da Pasta doc | acessar |
| Conteúdo da Pasta source | não têm arquivos |
| Conteúdo da Pasta agreement | não têm arquivos |
| 4. Condições de acesso e uso | |
| URL dos dados | http://urlib.net/ibi/8JMKD3MGP7W/383BFTB |
| URL dos dados zipados | http://urlib.net/zip/8JMKD3MGP7W/383BFTB |
| Arquivo Alvo | campos_does.pdf |
| Grupo de Usuários | alessandra@sid.inpe.br simone |
| Grupo de Leitores | administrator simone |
| Visibilidade | shown |
| Permissão de Leitura | allow from all |
| Permissão de Atualização | não transferida |
| 5. Fontes relacionadas | |
| Repositório Espelho | sid.inpe.br/mtc-m19@80/2009/08.21.17.02.53 |
| Unidades Imediatamente Superiores | 8JMKD3MGPCW/3EU29DP |
| Acervo Hospedeiro | sid.inpe.br/mtc-m19@80/2009/08.21.17.02 |
| 6. Notas | |
| Campos Vazios | archivingpolicy archivist callnumber copyholder copyright creatorhistory descriptionlevel dissemination doi edition editor format isbn issn label language lineage mark nextedition notes numberofvolumes orcid organization pages parameterlist parentrepositories previousedition previouslowerunit progress project publisher publisheraddress resumeid rightsholder schedulinginformation secondarydate secondarymark serieseditor session shorttitle sponsor subject tertiarymark tertiarytype type url volume |
| 7. Controle da descrição | |
| e-Mail (login) | simone |
| atualizar | |