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Increased wildland fires in southern California during the mid-21st Century
Yufang
Jin, University of California, yufang@uci.edu
(Presenter)
James
T.
Randerson, UC Irvine, Dept. of Earth System Science, jranders@uci.edu
Michael
Goulden, UC Irvine, mgoulden@uci.edu
Scott
Capps, UCLA, scapps@atmos.ucla.edu
Alex
Hall, UCLA, alexhall@atmos.ucla.edu
Southern California subjects to a large number of relatively small summer fires and a small number of extremely large Santa Ana (SA) fires in fall. Predicting future fires requires an improved understanding of the controls of both climate and extreme climatic events on burned area in different seasons. Here we built optimized empirical models to simulate the seasonal and interannual variation in number of fires and fire size for summer and SA fires, respectively. We combined California’s Fire and Resource Assessment Program historical fire perimeters, monthly PRISM climate data, and daily relative humidity (RH) and wind speed from a multi-decadal climate reconstruction with MM5 during 1959 - 2007. The number of summer fires was determined by the cumulative precipitation from previous three winter seasons and current RH, while the number of SA fires was mainly controlled by the number of SA events and RH. Wind speed was the most significant controls on SA fire size. We applied the models to the WRF 2 km climate data for the two time periods: 1980-2000 and 2040-2060 under RCP8.5 scenario, dynamically downscaled from the North American Regional Reanalysis climate data. Increases in summer temperature and decreases in relative humidity were projected to increase the number of summer fires by 20% in comparison to the base period. The average summer fire size was projected to increase more significantly by 37% mainly due to the decreasing RH, leading to a projected increase of burned area by 59%. Our preliminary studies showed the decreasing number of SA days and wind speed in the future. However, the projected decrease in fall and winter precipitation and the increase in the strength of the extreme SA events would increase the fire activity in the future. Our study suggests the value of different climate controls for predicting summer and SA fires and their potential impacts on fire and land management.
Presentation Type: Poster
Session: Poster Session 2-A
(Wed 11:00 AM)
Associated Project(s):
Poster Location ID: 49
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