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University of Nevada, Las Vegas (2021)

Linking Extreme High Air Temperature Events to Wildfire and Environmental Variation to Water Balance Partitioning in the Western US

Savage Neil

Titre : Linking Extreme High Air Temperature Events to Wildfire and Environmental Variation to Water Balance Partitioning in the Western US

Auteur : Savage Neil

Université de soutenance : University of Nevada, Las Vegas

Grade : Master of Science (MS) 2021

Résumé partiel
Wildfire activity has increased across the western United States in recent decades, causing significant damage to ecosystem services and human communities. The Sierra Nevada region, in particular, has experienced substantial increases in the ignition frequency, severity, and extent of large wildfires. To partly disentangle the complex processes underlying wildfire risk, I developed a simple approach to link natural wildfire ignition patterns to changing seasonal temperatures and extreme high and low air temperature events across the Sierra Nevada region from 1992—2015. Extreme event analyses focused on the association between the magnitude and frequency of occurrence of extreme temperature events and wildfire ignition in spring, summer, and fall wildfire seasons, with a particular focus on contrasting these patterns between fire and non-fire locations. Temperatures increased over the study period, including those of extreme high and low temperature events. Generally, fire locations were more likely to experience extreme high temperature events and less likely to experience extreme low temperature events. During summer and fall, fire locations also experienced relatively hotter extreme high temperature events. Fire ignition probability was most strongly associated with the frequency of extreme high air temperature event occurrence in seasons preceding and including the spring, summer, and fall fire seasons. As the number of extreme high temperature events increased over these seasons, fire ignition probabilities increased substantially (maximum ignition increases of +1346% in spring, +265% in summer, and +148% in fall) and were consistent across the Sierra Nevada region. Thus, the sustained occurrence of extreme high air temperature events indicates increased wildfire risk, and ignition in summer and fall fire seasons may be further enhanced by hotter extreme events. Relationships between high temperatures and natural wildfire ignition can help to identify locations of increased wildfire risk, and to some degree minimize uncertainty associated with the multiple factors that shape wildfire characteristics. This insight can guide management actions to reduce wildfire risk across the Sierra Nevada region and in other similar ecoregions.

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Page publiée le 27 novembre 2022