Sazonalidade de ondas planetárias nos ventos meteóricos observados em São João do Cariri-PB e em Cachoeira Paulista-SP

Abstract

Dynamical characteristics of the terrestrial mesopause region can be observed from the atmospheric fields, such as wind and temperature. The purpose of this study was to contribute to a better understanding of mesopause dynamics of the equatorial and low latitude regions in the southern hemisphere, through the characterization of the wind flow between 80 and 100 km altitude. In this study we used wind observation data from mesosphere and lower thermosphere region (MLT), obtained from meteor radar measurements at São João do Cariri (7.4° S, 35° W) from July 2004 to December 2008 and at Cachoeira Paulista (22.7° S, 45.0° W) from January 2002 to July 2006 and from September 2007 to November 2008. From the spectral and harmonic analysis it was possible to identify presence of planetary-scale oscillations in the mean winds for two latitudes and to study their transient character, which allowed to elaborate a climatology of planetary oscillation signatures. The planetary wave with periods near 2-day, 6-7 days, 16 days and the 3-4 days equatorial waves, also known as ultra fast Kelvin wave, were focused in this study. The 2-day waves in the meteoric winds showed a seasonal cycle, with intense amplitudes after the southern summer solstice until the end of season, the 6-7 day oscillations had more intense amplitudes during August-November and presence with lower amplitudes during April-May in both sites. The 16-day oscillations showed no clear seasonality over C. Paulista, however, the Cariri amplitudes were intense from spring until mid-summer and weak from autumn until early austral winter. The 3-4 day oscillations showed amplifications intermittent throughout the year and it was not possible to identify a seasonal cycle over two sites.