Observação de oscilações de 3-4 dias através das emissões do airlow mesosférico em São João do Cariri (7,4ºS; 36,5ºW).

Abstract

In this work was investigated the occurrence of 3-4day oscillations in the 015577, O2b(0-1) and OH(6-2) mesospheric airglow emissions between January 1998 and July 2007, which have been attributed to ultra-fast Kelvin waves. The airglow emissions intensity and rotational temperature were measured by multichannel photometer installed at Sao Joao do Cariri (7.4°S, 36.5°W). The periodicities were identified by Lomb-Scargle periodogram. In a total of ninety one airglow observations periods which were analyzed temporal series, in forty six of them it was identified the presence of 3-4day oscillations. The most events (34%) was identified in the spring. The percentile amplitudes in the 015577 and O2b(0-1) emissions showed a larger variability than those observed in the OH(6-2) emission Moreover, it was observed that the percentile amplitudes, on average, grow with altitude. The absolute amplitudes in the rotational temperature are in good agreement whit those that would be caused by ultra-fast Kelvin waves around 90 km of altitude. The oscillations vertical wavelength showed an ample interval of variation, and, in twenty occasions the obtained values were in agreement with that already reported in the literature for ultra-fast Kelvin waves. Comparison of the results obtained by airglow emissions with that obtained by mesospheric winds measured at Sao Joao do Cariri between 2004 and 2005 showed that only in one of the five occasions the 3-4day oscillations exhibit everyone features compatible with ultra-fast Kelvin waves.