Publication Date

Spring 2024

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Meteorology and Climate Science

Advisor

Adam Kochanski; Angel Farguell Caus; Craig Clements

Abstract

This study investigates trends in fuel moisture content (FMC) across California from 2000 to 2021. It utilizes two distinct sources of FMC data: the Fuel Moisture Repository, which integrates live fuel moisture content (LFMC) observations, and a novel dead fuel moisture content (DFMC) reanalysis product which provides spatial fuel moisture maps by integrating dead fuel moisture observations and a fuel moisture model driven by gridded weather data. The analysis uncovered a general downtrend in FMC across California, with the exception of LFMC in the Northernmost regions and coarse DFMC. Despite the differing long-term FMC trends, all the regions experienced a two-fold more severe downtrend from 2017 to 2021 compared to the 22-year average. The decrease in DFMC, driven solely by atmospheric conditions, suggests a shift in long-term weather patterns, while LFMC, being more sensitive to climatological conditions, exhibits extreme variability linked to drought conditions. Although the analysis of the correlation between wildfire activity and LFMC indicates spatial variability in the critical LFMC threshold values among the regions, all of them oscillate around the published value of 79%. Analysis of DFMC during wildfires suggests a 10% fuel moisture threshold for ignition. This study contributes to existing literature by presenting a 22-year FMC dataset for California and rigorously analyzing FMC trends not previously explored. The findings enhance our understanding of FMC dynamics, drought impacts, and their crucial role in shaping wildfire risk across California.

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