CEDAR: Quantifying Mesospheric Gravity Waves and Associated Temperature Variability Over the Andes

该项目是一项新的实验研究，旨在量化重力波在南美洲，特别是安第斯山脉附近的中低层热层（MLT）区域（~80-100 km）的动力学、动量输运、沉积和后续强迫中的作用。安第斯地区是研究重力波对MLT动力学影响的绝佳天然实验室。在夏季的几个月里，主要的重力波强迫来自于大陆东部强雷暴引起的深层对流。在冬季，强烈的地形强迫占主导地位，由于强烈的盛行纬向风从太平洋向东吹来，突然遇到高耸的安第斯山脉。这就产生了已经在平流层中很好地测量到的大振幅波，但在MLT高度还没有得到明确的测量。理论上有充分的理由认为它们会深入中间层，尤其是在冬季。该项目将在智利Cerro Tololo （30.1 S, 70.8 W）部署并远程操作犹他州立大学雪松中间层温度成图仪（MTM），并将其作为Maui-MALT项目（2002-2006）非常成功的一部分所获得的丰富经验作为基础。MTM是一个强大的、高性能的CCD成像系统，旨在通过精确观测两个突出的气辉发射，近红外OH（6,2）中心靠近87公里，O2（0,1）大气波段，靠近94公里，提供重力波的关键温度和强度测量。这些数据提供了在MLT高度量化波传播、增长和耗散的独特能力。计划与Na风温激光雷达、流星雷达、全天成像仪和其他光学仪器配合进行这些新的测量，这些仪器是经过验证的仪器集群的一部分，已在毛伊- malt计划中成功使用。主要目标是：1)利用协调的波浪、风和温度测量，量化安第斯山脉上广谱波浪（包括重力波、潮汐和行星波）的影响和季节变化；2)对冬季MLT高度的山波进行了独特的调查，量化了它们的特征和相关的动量通量，并与夏季由于对流强迫的类似测量结果进行了比较。该项目更广泛的影响包括强烈的学生参与，这将有助于培养下一代研究人员在新的光学测量和图像处理技术。此外，重力波在驱动MLT的平均和可变结构方面的公认作用使得了解它们的各种贡献成为航空学界的一个高度优先事项。特别是，需要能够在最先进的模式中准确描述这些影响，这对于在可变太阳强迫和气候变化条件下预测它们的区域、季节和全球影响具有广泛的意义。

This project is a novel experimental investigation to quantify the role of gravity waves on the dynamics, momentum transport, deposition and subsequent forcing of the Mesosphere and Lower Thermosphere (MLT) region (~80-100 km) over South America, and specifically near the Andes Mountains. The Andes region is an excellent natural laboratory for investigating gravity wave influences on the MLT dynamics. During the summer months the dominant gravity wave forcing results from deep convection arising from severe thunderstorms over the continent to the east. During the winter, strong orographic forcing dominates, due to intense prevailing zonal winds blowing eastward from the Pacific Ocean which suddenly encounter the towering Andes mountain range. This creates large amplitude waves that have been measured well into the stratosphere but have yet to be unambiguously measured at MLT heights. There are strong theoretical reasons to expect them to penetrate well into the mesosphere, especially during the winter months. Building on extensive experience gained as part of the highly successful Maui-MALT program (2002-2006), this project will deploy and remotely operate the Utah State University CEDAR Mesospheric Temperature Mapper (MTM) at Cerro Tololo, Chile (30.1 S, 70.8 W). The MTM is a robust, high-performance CCD imaging system designed to provide key temperature and intensity measurements on gravity waves using precise observations of two prominent airglow emissions, the NIR OH(6,2) centered near 87 km, and the O2(0,1)Atmospheric band, near 94 km. These data afford a unique capability to quantify wave propagation, growth, and dissipation at MLT heights. It is planned to perform these new measurements in coordination with Na wind-temperature lidar, meteor radar, all-sky imager and other optical instruments as part of a well proven instrument cluster, as employed successfully during the Maui-MALT program. The primary goals are: 1) To quantify the impact and seasonal variability of a broad spectrum of waves (including gravity waves, tides and planetary waves) over the Andes using coordinated wave, wind, and temperature measurements; 2) To perform a unique investigation of mountain waves present at MLT heights during winter months, quantifying their characteristics and associated momentum fluxes, and comparing with similar measurements during the summertime due to convective forcing. The broader impact of the project includes strong student involvement, which will contribute to training the next generation of researchers in novel optical measurements and image processing techniques. In addition, the recognized role of gravity waves in driving the mean and variable structure of the MLT makes an understanding of their various contributions a high priority for the aeronomy community. In particular, the need to be able to accurately describe these effects in state-of-the-art models has broad implications for predicting their regional, seasonal and global influences under variable solar forcing and climate change conditions.