Stratospheric Gravity Wave Study During the 2019 South American Solar Eclipse

日食是罕见而引人入胜的自然事件，它提供了在许多物理科学领域推进知识的机会。在大气中，日食在中性密度(重力波)中产生扰动，可以在水平和垂直方向上传播很长距离，并携带大量能量。重力波还可以与一般大气环流(即风)相互作用并改变它们。虽然高层大气中日食期间产生的重力波已经有了很好的记录，但在对流层和平流层高度产生的重力波实际上仍然没有被探索过。最近在2017年美国大日食期间的观测产生了关于日食产生的平流层重力波(SGW)的新的实验信息。2019年南美洲的日食提供了一个独特的机会，可以在这项工作的基础上再接再厉，获取日食产生的SGW的详细物理特征，并探索它们的生成机制。与智利塞罗帕雄的安第斯激光雷达观测站合作，气球携带的无线电探空仪将用于测量日食之前、期间和之后中性大气中的扰动水平。本科生将在2019年夏季参与这个项目10周，包括活动前5周的培训，在南美为期一周的活动，以及4周专注于活动期间收集的数据分析。该提案将支持蒙大拿大学的一名研究生领导数据分析工作并操作无线电探空仪系统。2019年活动的主要目标是专门关注日食期间平流层重力波的测量。日食前的时间分辨率越高，探测概率越高。2019年的活动被设计为从日食前24小时开始在不同高度放置两个气球，在完全黑暗(全食)的前一天晚上，两个气球中至少有一个在25-35公里范围内。7月2日下午晚些时候发射的时间将根据日食的不同阶段确定。与怀俄明州2017年日食无线电探空活动专注于特定大气层不同，2019年日食无线电探空活动的结构以及合作者的数据预计将产生日食产生的重力波的确凿证据和重要物理信息。这些数据将填补与重力波有关的观测空白，重力波是一种已知的向大气平均流传递动量和能量的机制。该奖项反映了NSF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。

Solar eclipses are rare and fascinating natural events that offer opportunities to advance knowledge in numerous areas of physical sciences. In the atmosphere, eclipses generate disturbances in the neutral density (gravity waves) that can propagate long distances in both horizontal and vertical directions and carry significant amounts of energy. Gravity waves can also interact with and modify general atmospheric circulation (i.e. winds). While gravity waves generated during solar eclipses in the upper atmosphere are well documented, their counterparts at the tropospheric and stratospheric heights remain virtually unexplored. Recent observations during the Great American Eclipse of 2017 have produced new experimental information about stratospheric gravity waves (SGWs) generated by a solar eclipse. The 2019 eclipse in South America offers a unique opportunity to build on this work and obtain detailed physical characterization of eclipse-generated SGWs and explore their generation mechanisms. Balloon-borne radiosondes in coordination with the Andes Lidar Observatory in Cerro Pachon, Chile will be used to measure disturbance levels in the neutral atmosphere prior to, during, and after the eclipse. Undergraduate students will be involved in this project for 10 weeks during summer of 2019 including five weeks of training before the event, the week-long campaign in South America, and four weeks focusing on analysis of data collected during the event. The proposal would support a graduate student at the University of Montana to lead the data analysis effort and operate radiosonde systems. The main objective of the 2019 campaign is to focus exclusively on stratospheric gravity wave measurements during an eclipse. Detection probability is enhanced with increased temporal resolution prior to the eclipse. The 2019 campaign is designed to have two balloons at various altitudes starting 24 hours before the eclipse, with at least one of the two balloons in the 25 - 35 km range every hour the night prior to the total darkness (totality). The timing of launches during the late afternoon of July 2nd will be based on phases of the eclipse. Unlike the Wyoming 2017 eclipse radiosonde campaign that focused on a specific atmospheric layer, the structure of the 2019 campaign along with collaborator data is expected to produce definitive evidence of and important physical information on eclipse-generated gravity waves. These data will fill the observational gap pertaining to gravity waves that are a known mechanism of momentum and energy transfer to atmospheric mean flow.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.