LAUSR

We analyze a large amplitude mountain wave event, which was observed by a ground-based lidar above New Zealand between 31 July and 1 August 2014. Besides the lidar observations, ECMWF data, satellite observations and raytracing simulations are utilized in this study. It is found that the propagation of mountain waves into the middle atmosphere is influenced by two different phenomena at different times during the event. At the beginning of the event, convective instabilities cause wave breaking in the lower stratosphere. During the course of the event the mountain waves propagate to higher altitudes and are refracted towards the polar night jet due to the strong meridional shear of the zonal wind. As the waves propagate out of the observational volume, the ground-based lidar observes no mountain waves in the mesosphere. However, raytracing simulations and satellite observations indicate that the waves reached mesospheric altitudes downstream of New Zealand. These results underline the importance of considering horizontal propagation of gravity waves when analyzing locally confined gravity wave observations.