The Quasi-Two-Day Wave Event of January 1984 and Its Impact on the Mean Mesospheric Circulation

Abstract

Studies of the quasi-two-day wave show that it is a summertime phenomenon. In the summer of 1983?84 at Adelaide (35°S, 138°E), the main phase of the wave appeared as a pulse in mid-January which lasted about seven cycles (14 days). Coincident with the onset of the pulse a temporary but substantial change occured in the prevailing circulation throughout a deep layer of the upper mesosphere; a perturbation of more than 10 m s under plausible assumptions about the magnitude of mean and eddy dissipation processes, predicted circulation changes agree reasonably well with those observed. It is concluded that such events have a substantial, if temporary, impact on the prevailing circulation in the upper mesospere and may be important in the transport of atmospheric constituents at these heights during summer.