Identificação de ondas atmosféricas ultrarrápidas de Kelvin nos ventos meteóricos da alta mesosfera equatorial sobre São João do Cariri-PB (7,4°S; 36,5°O).

Abstract

Meteor wind measurements obtained from São João do Cariri-PB (7.4° S, 36.5° W), Brazil, during 2005, have been used to examine the ultra-fast Kelvin wave characteristics in the mesopause and lower thermosphere region. The hourly winds were subjected to wavelet analysis and the results revealed the presence of 3-4 days waves in four episodes along the year. The observed parameters were used to check if the 3-4 days oscillations satisfy the dispersion relation for Kelvin waves. The results showed that only the oscillations occurred in February-March and May-June (first and second events), are compatible with equatorial ultra-fast Kelvin wave propagation, with zonal wave number s = 1. During these two events, the zonal wind amplitudes reached maximum values of 25m/s and 20m/s respectively. The vertical phase structure showed descending phase, compatible with ascending wave energy, and vertical wavelengths of about 40 km were found for both events. Additionally, longitude-time structures of the oscillations with periods near 4 days for the temperatures by TIMED/SABER instrument obtained during the four episodes were used and the results indicated eastward phase propagation with zonal wavenumber 1. These results reinforced those obtained from meteor wind data for two first episodes. Comparisons have been make with those for others sites and already reported in the literature.