Enhanced Drought and Temperature associated with Climate Oscillations in California Wildfire Dynamics

We investigated the impacts of climate oscillations, specifically the El Niño-Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO), and the Boreal Summer Intraseasonal Oscillation (BSISO) on wildfire dynamics in California during the period 1991 to 2021. We used the Monitoring Trends in Burn Severity (MTBS) and the ERA5 reanalysis datasets to analyze wildfire frequency, severity, moisture deficit, and fire weather indices. Preliminary results show northern and central California had higher wildfire risks during the cold PDO phase. A reduced moisture level and an increased Fire Weather Index (FWI) characterized this period, signaling environments conducive to wildfire outbreaks. However, southern California exhibited a distinct pattern, with a minimal correlation between the Vapor Pressure Deficit (VPD) and FWI. Such observations insinuate the presence of other dominant environmental and climatic factors in the region, which might play a decisive role in modulating wildfire risks, thereby overshadowing the direct influence of atmospheric dryness on FWI. Results indicate the pivotal impact of RH on the moisture content of vegetation. This direct relationship hints at the potential of RH to act as a critical precursor for wildfire threats, suggesting its inclusion as an integral parameter in predictive models.

This research underscores the importance of considering large-scale climate drivers when forecasting and preparing for regional wildfire risks.