Gravity Wave Zoo: Citizen Science and Atmospheric Gravity Waves over Poker Flat, Alaska
and High-resolution Analysis of Mesospheric Instabilities on 31 March 2022 at Poker Flat
 

The Gravity Wave Zoo, a citizen science initiative, has enabled the classification of large-scale hydroxyl image datasets, highlighting occurrences of high-frequency atmospheric gravity waves (GWs), wave instabilities, and aurora. To-date, the project has recorded over 80,000 classifications from more than 2,800 volunteers, spanning four observing seasons and encompassing over 700,000 near-infrared (NIR) hydroxyl images of the Mesosphere and Lower Thermosphere (MLT) at approximately 87 km in altitude. We’ll discuss the first statistical analysis of Gravity Wave Zoo engagement and results, evaluating volunteer accuracy and reliability, as well as associations with the background winds of the MLT. These connections are enabled by data obtained using the Poker Flat Research Range (PFRR) hydroxyl imager (65°N 147°W), which covers a significant portion of the local, high-latitude MLT, and the Poker Flat Meteor Radar, which measures background winds coincident with atmospheric anomalies (GWs, instabilities, or aurora) observed by the imager. We highlight the advantages of citizen science in classifying large-scale MLT variability datasets and link Gravity Wave Zoo findings to the physical processes at play in the high-latitude night sky.

Atmospheric instabilities were observed directly on 31 March 2022 from Poker Flat, Alaska using both hydroxyl airglow imaging and sodium resonance lidar. Airglow imaging allowed for the measurement of horizontal wavelength, propagation direction, period, and an estimation of the vertical extent of the unstable layer. Simultaneous lidar data showed density fluctuations with a similar period and vertical wavelength. Together, these observations describe the instabilities in 3D. Lidar data also provided context about the background atmosphere, showing that there were localized regions where the Richardson number dipped below 0.25, the threshold required for the formation of Kelvin-Helmholtz instabilities. Instabilities were extracted from data using a series of Fourier and Morse wavelet transforms to isolate them from background gravity waves, ensuring that the analysis techniques were free of contamination.