Characteristics of gravity waves and influences of source conditions on mountain wave penetration into the stratosphere and mesosphere above New Zealand

Bernd Kaifler* and N. Kaifler, B. Ehard, A. Dörnbrack, S. Gisinger, M. Rapp, D. Fritts
German Aerospace Center, Institute of Atmospheric Physics

We present atmospheric gravity wave measurements obtained by a Rayleigh/Raman lidar at Lauder, New Zealand, during and after the Deep Propagating Gravity Wave Experiment (DEEPWAVE) campaign. Gravity wave characteristics are derived from 557 h of lidar data acquired over a period of five months in winter 2014. Enhancements in gravity wave activity occurred in sporadic intervals lasting a few days. We employ spectral analysis of lidar temperature measurements to detect and sort wave packets into specific classes corresponding to propagating gravity waves and quasi-stationary gravity waves (mountain waves). Large-amplitude mountain waves are detected during periods with high tropospheric wind speeds perpendicular to the Southern Alps. During the strongest event (29 July to 1 August) amplitudes in excess of 15 K were observed at 40 km altitude. Surprisingly, the largest response at mesospheric altitudes is observed for conditions with low to moderate mountain wave forcing. Large-amplitude mountain waves excited by large cross-mountain wind speeds often do not penetrate into the mesosphere, either due to refraction away from New Zealand or wave breaking and dissipation in the stratosphere.


*email: bernd.kaifler@dlr.de
*Preference: Oral