First Advisor

Paul Loikith

Term of Graduation

Summer 2024

Date of Publication

7-10-2024

Document Type

Thesis

Degree Name

Master of Science (M.S.) in Geography

Department

Geography

Language

English

Subjects

atmospheric rivers, California, precipitation, Upper Yuba, weather extremes

Physical Description

1 online resource (v, 45 pages)

Abstract

The United States state of California is vulnerable to both droughts and extreme precipitation events due to the timing and processes of precipitation in the region. California's annual precipitation is dependent on a few strong storms and in addition to its Mediterranean climate, leads to great variability in precipitation both within and across years. While efforts to reduce the impacts of extreme precipitation events have been implemented, forecasting for these events remains a challenge in regions with complex terrain and dynamic meteorological drivers. In order to improve forecasting and preparedness for such events, it is important to understand the range of atmospheric drivers that lead to extreme precipitation, particularly on a small scale. Here we aim to better understand the variety of meteorological mechanisms resulting in wet season (October–March) extreme precipitation in the Upper Yuba watershed of California from 1980 to 2021. We implement an Extended self-organizing maps (SOM) approach to cluster and evaluate integrated water vapor transport (IVT) patterns during and preceding extreme precipitation days as 12 distinct 5-day patterns. Patterns show a range of storm types, largely characterized by southerly to southwesterly moisture transport driven by anomalously low sea level pressure and 300 hPa geopotential heights. Pattern orientation and intensities vary, with greater IVT magnitudes generally associated with higher watershed precipitation. Some patterns also show relatively low moisture transport, indicating the presence of additional drivers of regional precipitation. The methodology and evaluation of this study can aid in improving hydrometeorological forecasting in the Upper Yuba and other societally important watersheds.

Rights

© 2024 Emma Nichole Russell

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/42593

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