Estudo de frentes mesosféricas na região equatorial / Study of mesospheric fronts in the equatorial region

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

An extensive study on mesospheric fronts was carried out by means of mesospheric airglow image observation at at São João do Cariri, PB (7,4oS; 36,5oW) from July 2004 to December 2005. All sky airglow images, meteor radar wind and TIMED/SABER satellite temperature data were used in order to investigate physical scenario of the mesospheric front. Three different types of fronts were identified: bores with wave train, wall, and solitary waves. In addition to these, some evidences were also observed such as, front generation and/or dissipation, front destruction by background wind, double fronts and various fronts in a same night. Main subject of the present study was to investigate physical characterizations of duct where the mesospheric front propagates. The most important result in the present work was that in most of the cases Doppler ducts generated by vertical wind shear and surround by evanescent regions were responsible for supporting the mesospheric front. Further to this, it was also revealed that a strong semi-diurnal tidal oscillation which generates wind shear around the mesopause region might have an important role in formation of the ducting condition. Thermal structures in the mesopause region over São João do Cariri was also investigated in order to study the mesospheric fronts. Double mesopause with temperature inversion layers were observed during the equinox seasons (February to May and August to October), what was not predicted by CIRA-86 model atmosphere. From the gravity wave vertical propagation conditions (dispersion relation), the role of the wind (vertical gradient) and the temperature inversion were investigated in order to find which is more important. It was concluded that the mesospheric inversion layers alone could not explain the ducting condition.

ASSUNTO(S)

atmospheric dynamic space geophysics temperatura da atmosfera gravity waves aeronomia aeronomy dinâmica da atmosfera geofÍsica espacial ondas de gravidade atmospheric temperature

ACESSO AO ARTIGO

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