Transverse waves in a post-flare supra-arcade

In this proceeding text we highlight the results of Verwichte, Nakariakov & Cooper (2005), which analysed observations of propagating transverse waves in an open magnetic field structure with the Transition Region And Coronal Explorer (TRACE). In particular, waves associated with dark tadpole-like sunward moving structures in the post-flare supra-arcade of NOAA active region 9906 on the 21^st of April 2002 are analysed. They are seen as quasi-periodic transverse displacements of the dark tadpole tails, with periods in the range of 90-220 s. Their phase speeds and displacement amplitudes decrease as they propagate sunwards. At a height of 70 Mm above the post-flare loop footpoints the speeds and amplitude are in the range of 110-220 km s^-1 and 250-900 km respectively. The waves are interpreted as propagating fast magnetoacoustic kink waves guided by a vertical, open structure.