ORCID Number

0000-0001-6900-7313

Date of Award

Summer 8-2024

Embargo Period

8-2025

Access Type

Thesis - Open Access

Degree Name

Doctor of Philosophy in Engineering Physics

Department

Physical Sciences

Committee Chair

Alan Liu

First Committee Member

Nicholas M. Pedatella

Second Committee Member

Gunter Stober

Third Committee Member

Michael P. Hickey

College Dean

Peter Hoffmann

Abstract

This dissertation investigates the mechanism by which the Earth's whole atmosphere couples from the bottom to the top, pole to pole. The work in this dissertation utilizes observational data and numerical simulations, with a particular emphasis on sudden stratospheric warming (SSW) events. The development of a new multi-static meteor radar at 30ºS, named Chilean Observation Network De MeteOr Radars (CONDOR), provides a key dataset for the present studies. Wind validation of this new radar system is performed across different sites and compared to a co-located sodium lidar. Wave-wave interactions in the mesosphere and lower thermosphere (MLT) that may be responsible for the penetration of six-day periodicities into the Earth's ionosphere during the 2019 Southern Hemispheric (SH) SSW are first investigated. This study comprises two main findings. The quasi-6-day wave (Q6DW) amplifies the diurnal tide amplitudes every 6 days through nonlinear interactions, producing a particularly strong 21-hour child wave. This Q6DW-diurnal tide nonlinear interaction presents the first possible mechanism for the previously reported ionospheric 6-day variability. The second mechanism involves Q6DW modulation on gravity waves (GWs). A quasi-6-day periodicity in GW meridional variances is apparent and the upward propagation of GWs could carry the planetary wave periodicity directly into the ionosphere. The different behaviors of interhemispheric couplings (IHCs) related to Northern Hemispheric (NH) major SSWs in different boreal winter sub-seasons are also investigated based on 42 years of SD-WACCM-X simulation and 20 years of Aura MLS observation. The residual mean meridional and zonal circulation, parameterized GW forcing, and resolved planetary and tidal forcing represent intra-seasonal changes during NH major SSWs, which result in the different behaviors of IHCs. Warmings around the summer polar mesopause are more pronounced in the later boreal winter sub-seasons compared to the earlier sub-season. In addition to typical IHC patterns, a cooling below the summer mesopause at SH high latitudes is found during late boreal winter sub-seasons and is attributed to the consequences of changes in residual mean circulation and GW forcing.

Additional Files
Qiao_GS9_Acceptance_GS_NP_AL_MH_EM.pdf (465 kB)
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