DARE-IDOWO, O.; DARE-IDOWU, Oluwakemi.
Résumé:
Investigation on sources of gravity waves observed in the Brazilian equatorial region on April 8, 2005. On 08 April 2005, a strong gravity wave activity (more than 3 hours) was observed in São João do
Cariri (7.4oS, 36.50W). These waves propagated to the southeast and presented different spectral
characteristics (wavelength, period and phase speed). Using OH airglow images, the parameters
of 5 observed gravity waves were calculated; the wavelengths ranged from ~90 to 150 km, the
periods from ~26 to 67 min and the phase speeds from 32 to 71 m/s. A reserve ray-tracing analysis
was performed to investigate the likely sources of these waves. The ray-tracing database was
composed of temperature profiles from NRLMSISE-00 model and SABER measurements and
wind profiles from HWM-14 model and meteor radar data. According to the ray path, the likely
source of these observed gravity waves was the Inter Tropical Convergence Zone with intense
convective processes taking place in the northern part of the observatory. Also, the observed
preferential propagation direction of the waves to the southeast could be explained using blocking
diagrams, i.e., due to the wind filtering process.
