First Advisor

Paul Loikith

Term of Graduation

Spring 2021

Date of Publication

7-19-2021

Document Type

Thesis

Degree Name

Master of Science (M.S.) in Geography

Department

Geography

Language

English

Physical Description

1 online resource (vi, 43 pages)

Abstract

Projections of 500 hPa geopotential height (Z500) patterns over the Pacific Northwest of North America and their associated surface temperature, precipitation, and frequency of occurrence are assessed using models from the 6th phase of the Coupled Model Intercomparison Project (CMIP6). The self-organizing maps approach is applied to reanalysis data from the Modern-Era Retrospective Analysis for Research and Applications, version-2 (MERRA-2) to cluster daily Z500 anomalies into 12 representative patterns that span the range of historical circulation patterns. CMIP6 data for daily Z500 anomalies are mapped to each node for historical and end of century global warming experiments, and the resulting differences in Z500 anomaly patterns, their associated temperature and precipitation, and pattern frequency occurrence are analyzed. Models project a reduction in the amplitude of Z500 anomalies, with majority model agreement on significant reduction found in JJA and SON. The largest temperature increases in DJF are found for patterns historically associated with anomalously cold weather, while the largest temperature increases in JJA are found in patterns historically associated with anomalously warm weather. Precipitation is found to generally increase across all seasons and patterns, however some historically wet JJA patterns become significantly drier. Significant changes in pattern frequencies are found across seasons, with a general decrease in frequency of highly amplified Z500 anomaly patterns compared to the recent historical climate.

Rights

© 2021 Graham Patrick Taylor

In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).

Persistent Identifier

https://archives.pdx.edu/ds/psu/36356

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