Wildland fires in Southern California: a temporal perspective

Yufang Jin, UC Irvine, yufang@uci.edu (Presenter)
James T. Randerson, UC Irvine, Dept. of Earth System Science, jranders@uci.edu
Michael Goulden, UC Irvine, mgoulden@uci.edu
Alex Hall, UCLA, alexhall@atmos.ucla.edu

Wildland fires are an inevitable component of many southern California’s ecosystems. The largest and most destructive fires in Southern California occur during intense Santa Ana wind events. Predicting how these fires and subsequent impacts on ecosystem recovery, air quality, and human health are likely to change in the future requires an understanding of how fire weather, vegetation, and land use control contemporary fires and how they interact. We examined the characteristics of fire frequency and fire size from seasonal, interannual to decadal time scales, and identified the main controlling factors for fires in Southern California. The data we used

includes historical fire perimeter data for 1950 – 2009 as reported in

California’s Fire and Resource Assessment Program (FRAP), climate data from PRISM, and a multi-decade reconstruction of climate at 6 km

resolution simulated with MM5.

Large fires (greater than 4,000 acres) accounted for less than10% of the total number of fires, but more than 50% of the burned area. Fire was most common in June to October and peaked in July, coincident with higher temperatures and lower precipitation. Both the seasonality of Santa Ana events and fuel flammability (as controlled by rainfall/soil moisture) resulted in the maximum fire size and burned area occurring in October. Number of fires and total area burned also varied year to year independently, further supporting that they were controlled by different factors. The 1980s had a relatively large proportion of small fires, coincident with the wettest period of the record. In contrast, the 2000-2009 was dominated by large fires. We found a shift to a later fire season, especially with respect to burned area, from 50s to recent decade, i.e. the proportion of October burned area increased over time. Our analysis implied that a shift of timing from wind, relative humidity, or rainfall regimes may affect the probability of large fires and total burned area.

Presentation Type:  Poster

Session:  Global Change Impact & Vulnerability   (Tue 11:30 AM)

Associated Project(s): 

• Jin, Yufang: Fires in Southern California: Interactions between climate change, ecosystems, and humans ...details

Poster Location ID: 218