Stratospheric Gravity Wave Study During the 2019 South American Solar Eclipse

University Of Montana, Missoula MT

Investigators

Abstract

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.