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

该合同将资助智利塞罗帕雄的安第斯激光雷达观测站的钠(钠)风温激光雷达的持续运行(S 30.25W，70.74W，ELEV。2530米)支持针对安第斯山脉上方重力波(GW)耗散过程所导致的中层顶大气不稳定和湍流结构形成的动力学的科学研究，其中GW事件是山区GW事件的丰富人口。ALO的Na激光雷达是一种最先进的共振荧光多普勒激光雷达，能够在80-105公里高度范围内(称为MLT区域)以优异的垂直和时间分辨率测量3D风、中性温度和Na密度剖面，并具有高精度。其他可能的W&amp；T激光雷达研究将包括将激光雷达观测扩展到较低的热层，在热层钠层相当频繁地出现的情况下，对海拔140公里处的风和温度进行测量。这些层的形成尚不清楚，将是该奖项的一个重要研究课题。ALO观测站的另一个有趣的应用是探测中间层和较低的热层温度和风廓线中的湍流尺度扰动，这些扰动与大气不稳定层的形成和GW事件的消散有关。一个非常有趣的问题是，这项研究的结果如何适用于其他行星大气，在这些大气中，同样的流体动力学问题也发挥作用，因为相同的能量转移机制适用于这些环境。这一机制将与低海拔气象系统相关的平移能量转移到对MLT高度有重要意义的热源，这种机制的细节尚不清楚。众所周知，这种转换过程与指数中性密度的下降有关。当GW结构传播到上层区域时，转换过程通过耗散过程发挥作用，本奖项将通过比较观测结果和以湍流结构的启动、发展和演变为中心的模拟研究的预测来定义该过程。与该奖项研究领域相关的另一个问题是有机会研究2019年发生在智利的日全食对大气的影响。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.