Date of Award

1-1-2018

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

College/School/Department

Department of Atmospheric and Environmental Sciences

Content Description

1 online resource (ii, viii, 157 pages) : illustrations (some color)

Dissertation/Thesis Chair

Andrea L Lang

Committee Members

Ryan D Torn, Brian H Tang, Brian EJ Rose, Lorenzo M Polvani

Keywords

blocking, stratosphere, sudden stratospheric warmings, troposphere-stratosphere interaction, wave activity flux, Stratosphere, Atmospheric waves, Atmospheric temperature, Tropospheric circulation, Tropospheric thermodynamics, Synoptic meteorology, Climatology

Subject Categories

Atmospheric Sciences

Abstract

Rapid breakdowns of the climatological mid-winter stratospheric polar vortex [i.e., sudden stratospheric warmings (SSWs)] are often preceded by tropospheric blocks. While some studies suggest that blocks can induce the upward wave activity flux (WAF) through the tropopause region that is necessary to trigger an SSW, other studies show no statistical relationship between tropospheric blocks and SSWs. One objective of this dissertation is to elucidate the dynamical relationship between tropospheric blocks and SSWs by exploring the relationship between blocks and tropopause-level upward WAF. Along with analyzing blocks, this dissertation also explores rapidly deepening extratropical cyclones (i.e., bombs) and tropical cyclones that undergo extratropical transition (ET), as both have the potential to rearrange the tropopause waveguide into a configuration favorable for upward WAF. Using the MERRA-2 dataset, this dissertation identified 288 blocks, 876 bombs, and 128 ET events during the cool seasons of 1980-2015. The case-lists were then used to explore the relationship between synoptic events and stratospheric variability.

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