(März 1998)

Two mechanisms of the development of the wave are discussed: Salby (1981a,b) proposes that the quasi-2-day wave is a resonant ampliÆcation of the antisymmetric (3,3)-normal mode. Plumb (1983), however, suggests that the wave appears due to baroclinic instability near the summer stratospheric wind jet. The climatology of the quasi-2-day wave at Collm was described in detail by Jacobi et al. (1997c), who also pointed out that an influence of the 11-year solar cycle on its amplitude could be seen.

In the following, mesopause wind data measured at the Collm Observatory of the University of Leipzig are investigated with respect to a possible solar cycle dependence.