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°S, 68°W) and the SuperDARN high-frequency meteor-wind radars at Halley (76°S, 27°W), Sanae (72°S, 3°W) and Syowa (69°S, 40°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 (τ ≈ 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 (τ ≈ 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.