Recent Observations of Small-Scale Gravity Waves at the Brazilian Antarctic Station (62°S)

The Sub-Antarctic Islands and the Drake Passage are known as a "hotspot" of gravity wave activity, which extends from the troposphere to the mesosphere. An all sky airglow imager and a new-generation meteor radar were installed at Comandante Ferraz Antarctic Station (62°S), also known as EACF (acronym in Portuguese), in the beginning of 2010. A new data set of small-scale gravity waves observed by an OH airglow imager is currently been characterized. The initial results show similar characteristics to the waves reported for the 2007 campaign. Figure 1 (A) shows one example of observed gravity wave at Ferraz Station on May 10, 2010. The spectral analysis of this wave event is presented in Figure 1 (B). In this case, the horizontal wavelength and wave period, estimated based on the spectral analysis, were of about 29 km and 20 minutes, respectively. The hourly mean winds inferred from a co-located meteor radar are used to access the intrinsic gravity wave parameters, and also to characterize the vertical propagation of the observed waves. This later characterization was not performed as desired for the waves identified in 2007, since there was no local wind measurement in that time. This work will present the initial results for the gravity waves observed in 2010 and some wave events identified in 2011, including its observed and intrinsic parameters, propagation direction and examples of vertical profiles of m2. The later parameter is obtained only for the altitude range on which the winds are properly estimated by the meteor radar.