Mountain Wave Breaking Regions Leading to Secondary Gravity Wave Generation during the Deep Propagating Gravity Wave Experiment (DEEPWAVE)

Several occurrences of secondary gravity wave generation due to mountain wave breaking regions were observed during the DEEPWAVE airborne field program performed over New Zealand during June and July 2014. Measurements utilized a Rayleigh lidar, sodium lidar, and Advanced Mesospheric Temperature Mapper (AMTM) built for the NSF/NCAR Gulfstream V specifically for DEEPWAVE. Mountain wave breaking was observed in both the stratosphere, and in the mesosphere and lower thermosphere (MLT) region at ~80-100 km. In both regions, secondary gravity waves were observed at similar and smaller scales to the initial mountain waves. On 29 June 2014, mountain wave breaking regions at ~35-45 km were observed on several passes over the Southern Alps. Above these regions, secondary gravity waves were observed in the Rayleigh lidar temperatures. These events are compared with WRF simulations, confirming the mountain wave breaking regions and potential for secondary gravity wave generation. Mountain wave breaking regions were also observed in the MLT on 13 July 2014 in the sodium lidar and AMTM, and secondary gravity waves were similarly observed during this event.