| Journal: | Revista brasileira de geofisica |
| Database: | PERIÓDICA |
| System number: | 000335167 |
| ISSN: | 0102-261X |
| Authors: | Lima, Lourivaldo Mota1 Medeiros, Amauri Fragoso de2 Buriti, Ricardo Arlen2 Batista, Paulo P3 Clemesha, Barclay Robert3 Takahashi, Hisao3 |
| Institutions: | 1Universidade Estadual da Paraiba, Departamento de Fisica, Joao Pessoa, Paraiba. Brasil 2Universidade Federal de Campina Grande, Campina Grande, Paraiba. Brasil 3Instituto Nacional de Pesquisas Espaciais, Sao Jose dos Campos, Sao Paulo. Brasil |
| Year: | 2007 |
| Volumen: | 25 |
| Pages: | 43-48 |
| Country: | Brasil |
| Language: | Inglés |
| Document type: | Artículo |
| Approach: | Analítico, descriptivo |
| English abstract | Simultaneous observations of the atmospheric neutral winds in the mesosphere and lower thermosphere (MLT) by meteor radar have been carried out at S˜ao Jo˜ao do Cariri (7.4◦S, 36.5◦W) and Cachoeira Paulista (22.7◦S, 45.0◦W). From the wind variability we investigate the atmospheric planetary-scale quasi-two-day waves, which were present at both the sites during the winter of 2004 and summer of 2004/2005. The amplitude of the meridional component was larger than that of the zonal component, reaching a maximum value of 60 m/s at the equatorial site and 25 m/s at the low latitude site during the winter. During the January-February period the 2-day wave was very similar at the two sites, with a maximum amplitude of 50 m/s. The phase propagation with height shows a descending mode and upward energy propagation. The vertical wavelength estimated for Cachoeira Paulista (40-67 km) was longer than for S˜ao Jo˜ao do Cariri (30-35 km), for all of the observed events. Cross-spectral analysis showed a significant coherence between the quasi-two-day oscillations observed at the two sites. From the phase difference between the two sites we concluded that S˜ao Jo˜ao do Cariri leads Cachoeira Paulista. These results denote that amplitude peak at 36.5◦W and subsequently at 45◦W, compatible with a westward propagating wave |
| Portuguese abstract | Este trabalho tem como base medidas dos ventos da parte superior da mesosfera e da baixa termosfera obtidas simultaneamente atraves de radares meteoricos em S˜ao Jo˜ao do Cariri (7.4◦S, 36.5◦O) e Cachoeira Paulista (22.7◦S, 45.0◦O). As ondas atmosfericas de escala planetaria com perıodos proximos de 2 dias sao investigadas, as quais estiveram presentes nos ventos das duas localidades durante o inverno de 2004 e verao de 2004/2005. As amplitudes das oscilacoes foram mais intensas na componente meridional, alcancando m´aximos de 60 m/s na localidade equatorial e 25 m/s na de baixa latitude durante o inverno. Durante o perıodo de janeiro-fevereiro a onda de 2 dias mostrou-se similar em ambas as localidades, com amplitude maxima de 50 m/s. A propagacao de fase com a altura foi descendente, compatıvel com propagacao ascendente de energia. Os comprimentos de onda verticais estimados para Cachoeira Paulista (40-67 km) foram maiores do que para Sao Joao do Cariri (30-35 km). An´alises de espectro cruzado mostraram coerˆencia significativa entre as oscilacoes de 2 dias nas duas localidades. Da diferenc¸a de fase entre as duas localidades verificouse que os maximos em Sao Joao do Cariri (36,5◦O) ocorrem antes do que os de Cachoeira Paulista (45◦O), indicando propagacao para a direcao oeste |
| Disciplines: | Geociencias |
| Keyword: | Ciencias de la atmósfera, Mesosfera, Radar, Meteoros, Viento, Ondas, Brasil |
| Keyword: | Earth sciences, Atmospheric sciences, Mesosphere, Radar, Meteors, Wind, Waves, Brazil |
| Full text: | Texto completo (Ver PDF) |
