Dissipation Rates of Mesospheric Stratified Turbulence From Multistatic Meteor‐Radar Observations

• Published in: Geophysical research letters Vol. 51; no. 11
• Main Authors: Vierinen, J., Poblet, F. L., Chau, J. L., Avsarkisov, V., Pécseli, H. L., Tsutsumi, M., Nozawa, S., Johnsen, M. G., Latteck, R., Gulbrandsen, N.
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 16.06.2024; AGU; Wiley
• Subjects: Atmosphere; Correlation; Correlation analysis; Earth; Eddy kinetic energy; Energy balance; Energy dissipation; Energy exchange; Energy flow; Isotropic turbulence; Kinetic energy; Lidar; Local flow; Lower mantle; Lower thermosphere; Maxima; Mesosphere; Mesospheric dynamics; Meteors; Meteors & meteorites; Radar; Radar backscatter; Radar data; Radar measurement; Satellite observation; Seasonal variability; Seasonal variation; Seasonal variations; Specific energy; Statistical analysis; Statistical methods; Statistics; Structure-function relationships; Thermosphere; Tracers; Turbulence; Turbulent energy; Turbulent fluctuations; Upper atmosphere; Velocity; Viscosity; Wind; Wind speed; Wind velocities; Winds; Norway
• ISSN: 0094-8276; 1944-8007; 1944-8007
• DOI: 10.1029/2023GL105751

Stratified turbulence (ST) has been proposed as a model for the dynamics of the mesosphere‐lower thermosphere (MLT) region. This theory postulates that for horizontal mesoscales (∼1–400 km), the kinetic energy of horizontal winds dissipates from large to small scales with an approximately mean constant rate. In this investigation, dissipation rates are quantified using meteor‐radar observations conducted in Northern Norway. The observed seasonal variability of dissipation rates exhibits maxima during the summer and winter, and minima near the equinoxes, between 80 and 95 km altitude. The results are compared with model predictions and earlier medium frequency radar, rocket, lidar, and satellite observations of MLT turbulence. The findings suggest that multi‐static meteor radar measurements of ST can provide a novel way to continuously monitor turbulent dissipation rates in the MLT region. Plain Language Summary Classical models of locally homogeneous, isotropic turbulence postulate that energy flows from large to small scales, in a series of small steps, until dissipated by viscosity. Despite the inherent chaos in individual flow realizations, certain statistical averages remain amenable to analytical modeling. Notably, the second‐order velocity structure function contains the specific energy dissipation rate as a crucial parameter. Empirical observations in both laboratory flows and nature support these theoretical frameworks. In this study, we leverage radar backscatter data to determine correlation functions of wind velocities in the mesosphere and lower thermosphere over northern Norway. The presence of short‐lived localized trails of ionized gas, left by small meteors as they enter Earth's atmosphere, facilitates the scattering of radar signals. These trails move with the local flow, serving as tracers for fluctuating neutral wind velocity. Our extensive dataset, covering a full year, forms the basis for a robust statistical analysis. By experimentally determining the velocity structure functions, we can estimate the energy dissipation rate. The findings from our analysis offer valuable insights into turbulent energy cascade, highlighting the significance of turbulent fluctuations in the dynamics and energy balance of Earth's upper atmosphere. Key Points Estimates of stratified turbulence dissipation rates, velocities,and horizontal length scales Seasonal and height variation of stratified turbulence dissipation rate and velocity Experimental verification of the Kolmogorov relationship for turbulent dissipation rate, velocity, and length scale