Determinação de parâmetros de ondas de gravidade, usando medidas de temperatura termosféricas.

Abstract

Atmospheric gravity waves are essential in to transport energy and momentum from the middle to upper atmosphere. These waves are able to destabilize the hydrostatic balance of the atmospheric fluid, in that the imbalance between the gravity and buoyancy acts as the main restoring force. In this work, temperature data has been used, which were collected by two Fabry-Perot interferometers (FPI), which measure emissions of the red line of atomic oxygen - OI630.0 nm during the night, one located in São João do Cariri (7,4 ◦ S; 36.5◦ W) and one in Cajazeiras (6.8 ◦ S; 38.5◦W) during 2013. Gravity wave parameters were estimated, such as amplitude, period, horizontal wavelength and horizontal phase propagation direction in the thermosphere-ionosphere region at altitude around 250 km. The Lomb-Scargle periodogram and wavelet analysis were used to determine the parameters of the observed waves. To obtain amplitudes and phases, the data were subjected to harmonic analysis using the least squares method. After analyzing 340 nights for Cajazeiras and 346 for São João do Cariri, a total of 14 and 27 events were observed, respectively, with wavelengths ranging from 18 to 938 km, with periods between 35.4 min and 155.4 min, and mean amplitude ranging from 3.84 K to 130.6 K. It was also noted that the observed waves propagated preferentially between the northeast and the southeast.