Date of Award:

12-2024

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Physics

Committee Chair(s)

Tao Yuan (committee chair)

Committee

Tao Yuan

Committee

Boyd Edwards

Committee

Jan Sojka

Committee

Ludger Scherliess

Committee

Charles Swenson

Abstract

Atmospheric gravity waves are ubiquitous and important events in Earth’s atmosphere with impacts on space weather and associated technological effects. The population of gravity waves is determined by their formation mechanisms, and their interactions with the background atmosphere. These gravity waves transport energy and momentum into the near Earth space environment, and are responsible for movement of chemical species. Predicting the occurrence of space weather effects, then, is in part a process requiring the characterization of gravity waves. Case studies of unique and interesting gravity wave events are an important part of this process. These allow for the investigation of new interactions and dynamics that may be hypothesized and documented in literature, but perhaps not in observation. Another critical component is the characterization of the overall gravity wave population and determination of the background climatology. One method which may be used to do this is the hodograph method, which is well suited for application to lidar data sets. The hodograph method uses the altitude profile of horizontal wind to obtain gravity wave parameters. Although this method has been used in previous studies, a comparison of gravity wave parameters with a coincident and independent instrument has not yet been conducted. The studies presented here build on the history of collaborative studies between the USU Na lidar and USU AMTM to answer questions naturally arising from an unusual gravity wave. The first is a case study of a unique wave event observed by the USU AMTM on the night of 11 September, 2016 using Na lidar data to characterize the overall background. This study concludes, in part, by speculating that there may be a medium scale gravity wave present which interacts with the small scale wave in such a way as to cause the unique behavior observed by the AMTM. The second study compares horizontal wave parameters for medium-scale candidate gravity waves (periods between 1 and 6 hours) characterized by AMTM Keogram analysis and the Hodograph method applied to USU Na lidar data on the night of 24 September, 2014. Finally, the first study will be revisited using the Hodograph method shown in the second study to characterize the medium scale gravity wave hypothesized by the first study. Together these studies show, respectively, the first evidence for the horizontal blocking of a small scale gravity wave as discussed in theory and modeling studies, that the hodograph method can be used to accurately characterize waves also observed by the AMTM, and that the medium scale wave suggested by blocking theory, modeling, and hypothesized in the first study was confirmed to be present using USU Na lidar hodograph analysis.

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