The role of Stratified Turbulence in the Middle Atmosphere

• Applicant: Dr.-Ing. Victor Avsarkisov, Ph.D.
• Subject Area: Atmospheric Science ; Fluid Mechanics
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 520013270

This project is devoted to the study of stratified turbulence in the middle atmosphere. Our recent investigation of the gravity wave breaking process confirmed the existence of a strongly stratified turbulence regime in the winter mesosphere. This study involved a theory of stratified turbulence and utilized state-of-the-art measurements from a sounding rocket experiment WADIS-2 and a new gravity wave resolving version of the Kühlungsborn Mechanistic General Circulation Model. This identification of the strongly stratified turbulence regime suggests that a new family of hydrodynamic instabilities, known from laboratory experiments and theoretical considerations, is present in the middle atmosphere. As a part of mesoscale dynamics, stratified turbulence is one of the most active dynamical regimes in the middle atmosphere. The existence of this turbulence regime also has significant outcomes reaching the scale of weather and global climate, which became our motivation for the current proposal. The recent progress in instrument development at the Institute of Atmospheric Physics (IAP, Kühlungsborn) has allowed us to observe the dynamics at vertical scales below 500 meters and to perform simultaneous three-dimensional velocity and density measurements in the middle atmosphere. These unique worldwide high-precision measurements are essential for understanding small-scale dynamical processes such as coupling between gravity waves and stratified turbulence, layering, and mixing in the stratified and sheared atmosphere. Within this project, we plan to utilize these high-resolution measurements and numerical simulations (GCM and DNS) to address the problem of mesoscale dynamics in the middle atmosphere. Our primary aim in this project is to understand the dynamics at horizontal scales below 100 km and vertical scales below 5 km in the middle atmosphere. And the ultimate goal is to propose a method to parametrize these processes for implementation in NWP models and GCM. This project also has explicit multidisciplinary nature, as the problem we want to attack is fundamental for atmospheric physics, oceanography, environmental fluid dynamics, and theoretical considerations of stratified turbulence. Besides, the strength of the stratified turbulence regime in the atmosphere is much greater than in laboratory experiments. With this project, we will show that the middle atmosphere is a perfect fluid dynamics laboratory to analyze and further develop the theory of stratified turbulence.

• DFG Programme: Research Grants
• International Connection: Poland, Spain, USA
• Co-Investigators: Professor Jorge Chau, Ph.D.; Professorin Dr. Claudia Stolle
• Cooperation Partners: Professor Dr. Erich Becker; Professor Sergio Hoyas, Ph.D.; Dr.-Ing. Marta Waclawczyk