- 1Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University, Beijing, China (xiaocunying@bnu.edu.cn)
- 2School of Physics and Astronomy, Beijing Normal University, Beijing, China
The Mesosphere and Lower Thermosphere (MLT) act as a critical region for the propagation and dissipation of atmospheric waves, such as gravity waves, tides, and planetary waves, playing a significant role in the global atmospheric circulation system. These waves, particularly gravity waves, dissipate and break in the MLT, converting their energy into turbulence and generating localized turbulent structures. The turbulence produced in turn can modulate wave propagation, with part of the dissipated energy potentially re-exciting new waves. Atmospheric turbulence in the MLT significantly influences the transport of energy, momentum, and matter, making it a key mechanism for understanding the coupling across the entire atmospheric system. The studies of MLT atmospheric turbulence can also promote the fine modeling of the middle and upper atmosphere.
By integrating ground-based MF radar observations over (39.4°N, 116.7° E) with TIMED/SABER satellite data, we investigated the variations of atmospheric turbulence energy dissipation rate (ε) and the turbopause, as well as their relationship with atmospheric wave dynamics in the MLT region. Results show that the atmospheric ε is modulated by different periods at different altitudes. The ε is subject to 12 h and 24 h periodic variations. The 12 h periodic variation is more obvious at higher altitudes than the 24 h periodic variation at lower altitudes with the dividing layer at about 90 km. Advanced analysis of turbopause are based on the total wave variations based on SABER/TIMED. We first propose a new method for identifying the wave-turbopause by employing the conservation of energy principle, and introducing an energy index to delineate the turbopause layer’s boundaries. This method defines a set of parameters including the lower boundary height, upper boundary height, turbopause height, and turbopause layer thickness. Applying this method to long-term SABER data over Beijing, we find that the turbopause layer exhibits distinct seasonal and interannual variations. The average heigh of lower boundary is 69 km, and the average heigh of upper boundary is 94 km. Global characteristics of the turbopause layer are provided, which are quite valuable to enhancing our further atmospheric modeling and empirical studies.
How to cite: Xiao, C.: The Activity of Atmospheric Turbulence in the MLT, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20108, https://doi.org/10.5194/egusphere-egu25-20108, 2025.