ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-11-12137-2011 Observation of a mesospheric front in a thermal-doppler duct over King George Island, Antarctica Bageston J. V. 1 Wrasse C. M. 2 Batista P. P. 1 Hibbins R. E. 3 C Fritts D. 4 Gobbi D. 1 Andrioli V. F. 1 Instituto Nacional de Pesquisas Espaciais (INPE), São José dos Campos, Brazil Vale Soluções em Energia (VSE), São José dos Campos, Brazil British Antarctic Survey (BAS), Cambridge, UK, and Norwegian University of Science and Technology (NTNU), Trondheim, Norway Colorado Research Associates (CoRA), Boulder, USA 07 12 2011 11 23 12137 12147 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/11/12137/2011/acp-11-12137-2011.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/11/12137/2011/acp-11-12137-2011.pdf

A mesospheric front was observed with an all-sky airglow imager on the night of 9–10 July 2007 at Ferraz Station (62° S, 58° W), located on King George island on the Antarctic Peninsula. The observed wave propagated from southwest to northeast with a well defined wave front and a series of crests behind the main front. The wave parameters were obtained via a 2-D Fourier transform of the imager data providing a horizontal wavelength of 33 km, an observed period of 6 min, and a horizontal phase speed of 92 m s<sup>−1</sup>. Simultaneous mesospheric winds were measured with a medium frequency (MF) radar at Rothera Station (68° S, 68° W) and temperature profiles were obtained from the SABER instrument on the TIMED satellite. These wind and temperature profiles were used to estimate the propagation environment of the wave event. A wavelet technique was applied to the wind in the plane of wave propagation at the OH emission height spanning three days centered on the front event to define the dominant periodicities. Results revealed a dominance of near-inertial periods, and semi-diurnal and terdiurnal tides suggesting that the ducting structure enabling mesospheric front propagation occurred on large spatial scales. The observed tidal motions were used to reconstruct the winds employing a least-squares method, which were then compared to the observed ducting environment. Results suggest an important contribution of large-scale winds to the ducting structure, but with buoyancy frequency variations in the vertical also expected to be important. These results allow us to conclude that the wave front event was supported by a duct including contributions from both winds and temperature.

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