Date of Award

12-2025

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Degree Statement

Doctor of Philosophy in Atmospheric Sciences

Department

Department of Atmospheric Sciences

Committee Chair

Collins, Richard

Committee Member

Polyakov, Igor

Committee Member

Thorsen, Denise

Committee Member

Williams, Bifford

Committee Member

Fochesatto, Javier

Table of Contents

Chapter 1: Introduction

Chapter 2: Three-channel Rayleigh system signal retrievals 

Chapter 3: Multi-year temperature measurement of the polar middle atmosphere at Chatanika, AJ using Rayleigh density and temperature lidar

Chapter 4: Estimation of gravity wave activity using the interleaved method 

Chapter 5: Ensemble of gravity waves in the middle atmosphere 

Chapter 6: Methodologies to find intrinsic characteristics of monochromatic waves 

Chapter 7: Monochromatic waves in the middle atmosphere 

Chapter 8: General conclusions

Abstract

The middle atmosphere, spanning the stratosphere and mesosphere, plays a critical role in global atmospheric circulation, particularly in the Arctic, where phenomena like Sudden Stratospheric Warmings (SSW) significantly perturb the circulation patterns. This dissertation investigates the dynamics of the polar middle atmosphere using four-year (20218-2022) temperature and wave activity measurements collected by the three-channel Rayleigh Density Temperature Lidar, Sodium Resonance Wind-Temperature Lidar, and Poker Flat Meteor Wind Radar at Poker Flat Research Range, Chatanika, Alaska (650N,1470W). The primary contributions are the development of a new lidar signal retrieval technique to combine the signal from three-channels and improve the lidar signal quality, adoption of an interleaved processing method to remove instrumental noise, and development of methods to determine intrinsic parameters of Atmospheric Gravity Waves (AGW) based on measurements at two altitudes. The temperature observations show evidence of vertical coupling with stratospheric warming and mesospheric cooling during SSWs. The wave activity associated with the ensemble of AGWs (30 min-4 h, 2km- 20 km) is reduced over periods of greater than a month during the 2018-2019 SSW. This reduction of AGW activity is evident from 40 km to 65 km and is associated with critical layer filtering. Analysis of monochromatic AGWs indicates that while the waves are stable, they are dissipating with altitude and contribute to the forcing of the circulation through their momentum fluxes. These results provide fundamental insight into the wave dynamic that shapes the high- latitude general circulation.

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