Collaborative Research: Instabilities and Turbulence in Gravity Wave Dissipation and Formation of Thermospheric Sodium Layers above the Andes

点击翻译按钮获取中文摘要

This award will fund continued operations of a sodium (Na) wind-temperature (W&T) lidar at the Andes Lidar Observatory (ALO) in Cerro Pachon, Chile (30.25 S, 70.74 W, elev. 2530 m) supporting scientific studies aimed at the dynamics of mesopause atmospheric instabilities and turbulence structures formation resulting from the gravity wave (GW) dissipation processes for a spatial region above the Andes where the population of mountain GW events is abundant. The Na lidar at ALO is a state-of-the-art resonance-fluorescence Doppler lidar, capable of measuring 3D wind, neutral temperature and Na density profiles with excellent vertical and temporal resolutions within the 80-105 km altitude range (referred to as the MLT region) and with high accuracy. Other possible W&T lidar studies would include the extension of lidar observations into the lower thermosphere, with wind and temperature measurements up to 140 km altitude for the somewhat frequent occurrence of thermospheric sodium layers. The formation of such layers is not understood and will be a significant topic of research in this award. Another interesting application of the ALO observatory is the detection of turbulence scale perturbations in the mesosphere and lower thermosphere temperature and wind profiles that are related to the formation of atmospheric unstable layers and dissipation of GW events.A point of great interest was how the results of this research might be applicable to other planetary atmospheres where the same issues of fluid dynamics come into play because the same energy transfer mechanism applies to these environments. The details of this mechanism that transfers translational energy associated with meteorological systems at low altitudes into a heat source that is significant at MLT altitudes are poorly understood. This conversion process is known to be related to the decreasing exponential neutral density. As the GW structure propagates into the upper region, a conversion process comes into play through dissipation processes that this award would define by undertaking the comparison of observations with the predictions of modelling studies centered upon the question of the initiation, development, and evolution of turbulent structures. Another issue relating to this award area of study is the opportunity to study the atmospheric effects of a total solar eclipse that will be happening in 2019 in Chile.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.