Abstract
This work presents the characteristics of gravity waves observed over Comandante Ferraz Antarctic Station (EACF: 62.1° S, 58.4° W). A total of 122 gravity waves were observed in 34 nights from March to October 2017, and their parameters were obtained by using the Fourier Transform spectral analysis. The majority of the observed waves presented horizontal wavelength ranging from 15 to 35 km, period from 5 to 20 min, and horizontal phase speed from 10 to 70 ± 2 m·s−1. The propagation direction showed an anisotropic condition, with the slower wave propagating mainly to the west, northwest and southeast directions, while the faster waves propagate to the east, southeast and south. Blocking diagrams for the period of April–July showed a good agreement between the wave propagation direction and the blocking positions, which are eastward oriented while the waves propagate mainly westward. A case study to investigate wave sources was conducted for the night of 20–21 July, wherein eight small-scale and one medium-scale gravity waves were identified. Reverse ray tracing model was used to investigate the gravity wave source, and the results showed that six among eight small-scale gravity waves were generated in the mesosphere. On the other hand, only two small-scale waves and the medium-scale gravity wave had likely tropospheric or stratospheric origin, however, they could not be associated with any reliable source.
Highlights
Atmospheric gravity waves (GWs) are considered to play an important role in the transport of energy and momentum, coupling the distinct atmospheric layers, contributing to the mix of mass and modifications in temperature and global circulation processes
It can be seen that the most wave events occurred from April to July, and a total of 122 gravity wave events were observed in 34 nights with at least 2 h of clear sky condition in 2017
Other results obtained by airglow imaging near the Antarctic Peninsula, at Halley Station, as described by Nielsen et al [15] for observations carried out in 2000 and 2001, and recently by Matsuda et al [6], with data obtained at Halley Station in 2013, are similar to our results regarding the anisotropy in the gravity wave propagation directions
Summary
Atmospheric gravity waves (GWs) are considered to play an important role in the transport of energy and momentum, coupling the distinct atmospheric layers, contributing to the mix of mass and modifications in temperature and global circulation processes. Some of the waves generated in lower layers of the atmosphere can propagate all over the atmosphere gaining altitude, while grows in amplitude, and can reach the upper mesosphere and thermosphere without being filtered by the wind [7,8,9]. It is well known that gravity waves play an important role at lower levels of the atmosphere and influence weather and meteorological phenomena [10]. The work is complemented by blocking diagrams and ray tracing results which are compatible in terms of the generation and propagation of the investigated waves
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