Nonlinear interaction between diurnal tidal and 2-day wave in the meteor winds observed at cachoeira paulista-sp and são joão do cariri-pb, brazil: a case study

ABSTRACT . Simultaneous measurements of meteor winds obtained in S˜ao Jo˜ao do Cariri-PB and Cachoeira Paulista-SP, Brazil, during June-July 2008 were used to investigate the occurrence of nonlinear coupling between atmospheric wave modes. The wind spectrum showed the quasi simultaneous presence of spectral energy peaks in the periods near 16, 24 and 48 hours, consistent with the occurrence of interaction between 48-h and 24-h waves, and the generation of 16-h waves. From the bispectral analysis, it was possible to confirm the occurrence of a 16-hour secondary wave generated by non-linear coupling between the 2-day and diurnal tide primary waves. Keywords : atmospheric tide, bispectral analysis, meteor radar. RESUMO . Medidas simultâneas de ventos meteoricos obtidos em Sao Joao do Cariri-PB e Cachoeira Paulista-SP, Brasil, durante os meses de junho e julho de 2008, foram usadas para investigar a ocorrencia de acoplamento nao linear entre modos de ondas atmosfericas. Os espectros dos ventos evidenciaram a presenca quase simultânea de picos de energia espectral nos periodos de ∼ 16, ∼ 24 e ∼ 48 horas, compativeis com a ocorrencia de interacao entre as ondas de 48 e 24 horas, e a geracao da onda de 16 horas. Atraves de analise biespectral foi possivel confirmar que a onda secundaria de 16 horas foi gerada pelo acoplamento nao linear entre as ondas primarias de 2 dias e a mare diurna. Palavras-chave: mare atmosferica, analise biespectral, radar meteorico.