Date of Award

1-1-2016

Language

English

Document Type

Master's Thesis

Degree Name

Master of Science (MS)

College/School/Department

Department of Atmospheric and Environmental Sciences

Content Description

1 online resource (v, 41 pages) : color illustrations and color maps.

Dissertation/Thesis Chair

Aiguo Dai

Committee Members

Jiping Liu

Keywords

Droughts, Climatic changes, Precipitation (Meteorology), Greenhouse gases

Subject Categories

Atmospheric Sciences

Abstract

Hydroclimate changes over the Southern Central Great Plains (SCGP) of the United States have been occurring throughout the last century. These changes have had a major impact on the local ecosystems, agriculture, and human society in the region by, e.g., producing a higher frequency of drought over the last century. Climate models project further increases of drought in the 21st century over this region under increasing greenhouse gases. This study analyzes climate model simulations to examine changes in synoptic conditions associated with the projected drought increases over the SCGP. Synoptically, mesoscale convective complexes (MCCs) produce a large portion of the summertime rainfall over the SCGP. Together with a northward movement of the upper-level jet, these MCCs are projected to be displaced much further north of the SCGP region by the later part of the 21st century. Even though the low-level jet is projected to strengthen and bring more moisture into the SCGP, the activating factor for the MCCs could be diminished as the upper tropospheric synoptic conditions (including the polar jet stream) favorable for MCC formation are projected to be relocated further north. Thus, the northward movement of the upper-level jet stream and the MCCs are the key synoptic changes that lead to reduction in summer precipitation over the SCGP. Combined with increased evaporative demands for moisture associated with rising temperatures, this leads to large drying and increased frequency of drought over the SCGP in the 21st century under rising greenhouse gases in the atmosphere.

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