Momentum flux estimates accompanying multiscale gravity waves over Mount Cook, New Zealand, on 13 July 2014 during the DEEPWAVE campaign

Observations performed with a Rayleigh lidar and an Advanced Mesosphere Temperature Mapper aboard the National Science Foundation/National Center for Atmospheric Research Gulfstream V research aircraft on 13 July 2014 during the Deep Propagating Gravity Wave Experiment (DEEPWAVE) measurement program revealed a large‐amplitude, multiscale gravity wave (GW) environment extending from ~20 to 90 km on flight tracks over Mount Cook, New Zealand. Data from four successive flight tracks are employed here to assess the characteristics and variability of the larger‐ and smaller‐scale GWs, including their spatial scales, amplitudes, phase speeds, and momentum fluxes. On each flight, a large‐scale mountain wave (MW) having a horizontal wavelength ~200–300 km was observed. Smaller‐scale GWs over the island appeared to correlate within the warmer phase of this large‐scale MW. This analysis reveals that momentum fluxes accompanying small‐scale MWs and propagating GWs significantly exceed those of the large‐scale MW and the mean values typical for these altitudes, with maxima for the various small‐scale events in the range ~20–105 m2 s−2. Key Points Mountain waves penetrate the mesosphere under suitable propagation conditions Small‐scale gravity waves can attain very large momentum fluxes Occurrence of peak momentum fluxes is often dictated by multiscale environments