PMC Turbo: Studying Gravity Wave and Instability Dynamics in the Summer Mesosphere Using Polar Mesospheric Cloud Imaging and Profiling From a Stratospheric Balloon

Abstract

The Polar Mesospheric Cloud Turbulence (PMC Turbo) experiment was designed to observe and quantify the dynamics of small‐scale gravity waves (GWs) and instabilities leading to turbulence in the upper mesosphere during polar summer using instruments aboard a stratospheric balloon. The PMC Turbo scientific payload comprised seven high‐resolution cameras and a Rayleigh lidar. Overlapping wide and narrow camera field of views from the balloon altitude of ~38 km enabled resolution of features extending from ~20 m to ~100 km at the PMC layer altitude of ~82 km. The Rayleigh lidar provided profiles of temperature below the PMC altitudes and of the PMCs throughout the flight. PMCs were imaged during an ~5.9‐day flight from Esrange, Sweden, to Northern Canada in July 2018. These data reveal sensitivity of the PMCs and the dynamics driving their structure and variability to tropospheric weather and larger‐scale GWs and tides at the PMC altitudes. Initial results reveal strong modulation of PMC presence and brightness by larger‐scale waves, significant variability in the occurrence of GWs and instability dynamics on time scales of hours, and a diversity of small‐scale dynamics leading to instabilities and turbulence at smaller scales. At multiple times, the overall field of view was dominated by extensive and nearly continuous GWs and instabilities at horizontal scales from ~2 to 100 km, suggesting sustained turbulence generation and persistence. At other times, GWs were less pronounced and instabilities were localized and/or weaker, but not absent. An overview of the PMC Turbo experiment motivations, scientific goals, and initial results is presented here.

Comparative study between ground-based observations and NAVGEM-HA analysis data in the mesosphere and lower thermosphere region

“…Finally, and similar to previous studies (Fuller-Rowell et al, 2010, 2016, we attribute the day-to-day variability of the semidiurnal tidal amplitudes and phases to changes of the zonal winds in the middle atmosphere altering the vertical propagation conditions. Although atmospheric tides are global-scale waves, their vertical propagation depends on the regional meteorological situation.…”

“…We optimized these vertical wavelength values considering the results of previous studies using meteor radars investigating the vertical wavelengths of tides (Yu et al, 2013;Davis et al, 2013;Fritts et al, 2019). These earlier studies showed that the vertical wavelengths for most of the tidal modes are much larger than 25 km.…”

Four‐Dimensional Quantification of Kelvin‐Helmholtz Instabilities in the Polar Summer Mesosphere Using Volumetric Radar Imaging

“…For example, in the case of airglow imagers, the vertical dimension is not. To overcome the relative large thickness of the airglow layer of a few kilometers, high‐resolution ground‐ and balloon‐based images of noctilucent clouds (NLCs) have been recently shown to be useful to study KHI with high spatial and temporal resolution (e.g., Baumgarten & Fritts, ; Fritts et al, , ).…”

Comparative study between ground-based observations and NAVGEM-HA reanalysis data in the MLT region

“…The mean winds are regularized using a 10 km vertical retrieval kernel, the diurnal and semidiurnal tides are retrieved applying a 16 km vertical retrieval kernel. We optimized these vertical wavelength values considering the results of previous studies using meteor radars investigating the vertical wavelengths of tides (Yu et al, 2013;Davis et al, 2013;Fritts et al, 2019). These earlier studies showed that the vertical wavelengths for most of the tidal modes are much larger than >25 km.…”