MU radar observation of a mesospheric gravity wave breaking caused by convective instability

In recent measurements of mesospheric winds with the MU radar at Shigaraki (34.9 N, 136.1 E), Japan, a couple of wind velocity data was obtained showing that a monochromatic inertia-gravity wave was propagating vertically in the mesosphere. The data show that the velocity amplitude of the wave did not increase exponentially above a height and further show that the wave form had broken down at a level. Evaluating the changes of the atmospheric stability in the wave field from the measured wind data and from the estimated wave parameters, the breakdown of the wave was shown to be connected with the occurrence of convective instability in the wave field.