资源环境科技发展态势分析平台

Southern California's most extreme fire weather is caused by offshore Santa Ana winds, which commonly occur later in the year than the lightning which provides natural ignition. Examination of the specific dates of both lightning and Santa Ana winds over 25 years shows that Santa Ana winds are very rare during or even within ten days of lightning strikes. The median lag between the two phenomena is 52 days, and on those occasions when lightning does occur shortly before Santa Ana winds, the actual density of strikes is very low. The rarity of lightning as ignition for Santa Ana-driven fires suggests that the current fire regime dominated by such fires is largely a product of the abundance of human-caused ignition.