Mesospheric planetary waves over Antarctica during 2002

Wind measurements from a series of atmospheric radars located around Antarctica have been used to characterize the mesospheric planetary-wave field during the winter of 2002. Combining winds from the medium-frequency (MF) radar at Rothera (68 degrees S, 68 degrees W) and the SuperDARN high-frequency meteor-wind radars at Halley (76 degrees S, 27 degrees W), Sanae (72 degrees S, 3 degrees W) and Syowa (69 degrees S, 40 degrees E) stations, we have been able to measure the period, wavenumber and propagation direction of the most prominent planetary waves. The results show that the planetary-wave field before the unusual stratospheric warming in 2002 was dominated by a very long-period (tau approximate to 43 days), westward and upward-propagating zonal planetary wavenumber 1. However, after the stratospheric warming events began in late winter, the character of the wave field changed and a shorter period (tau approximate to 14 days), westward, zonal wavenumber 1 became established. It would appear that the previously reported oscillations of the mesospheric hydroxyl airglow temperatures at Rothera and Halley, which were strongly anti-correlated to the meridional wind, were the result of these planetary waves.