Summer and Fall Extreme Fire Weather Projected to Occur More Often and Affect a Growing Portion of California throughout the 21st Century

Abstract

Annual burned area has increased in California over the past three decades as a result of rising temperatures and a greater atmospheric demand for moisture, a trend that is projected to continue throughout the 21st century as a result of climate change. Here, we implement a bias-correction and statistical downscaling technique to obtain high resolution, daily meteorological conditions for input into two fire weather indices: vapor pressure deficit (VPD) and the Canadian Fire Weather Index System (FWI). We focus our analysis on 10 ecoregions that together account for the diverse range of climates, ecosystems, topographies, and vegetation types found across the state of California. Our results provide evidence that fire weather conditions will become more extreme and extend into the spring and fall seasons in most areas of California by 2100, extending the amount of time vegetation is exposed to increased atmospheric demand for moisture, and heightening the overall risk for the ignition and spread of large wildfire. The ecoregion-level spatial scale adopted for this study increases the spatial specificity of fire weather information, as well as the resolution with which fire and land managers can implement strategies and counter-measures when addressing issues related to climate change.

Bias correction and spatial disaggregation of satellite-based data for the detection of rainfall seasonality indices

“…These results are consistent with other findings; for instance, [12] spotted vast improvement in the monthly and seasonal rainfall values after bias correcting seasonal forecasts using BCSD method. [34] , recently also recorded similar results in Califonia where seasonal rainfall was well represented post BSCD. During the dry season (DJF), we observed that the BSCD was very good at bias correction, as very high values observed by the raw CHIRPS V2 in the southwestern parts of the country were well corrected to resemble those of the gauge.…”