Abstract The weather is an important driver of the wildfire incidence because it strongly influences fuel availability and flammability. In the Mediterranean climate, the spatial and temporal patterns of fire weather present high variability, which help to understand the variable fire regimes. To assess this link in the Iberian Peninsula and the role of fire weather on fire incidence variability, this work identified pyro-regions, characterized the fire regimes in these regions and compared them with the spatial and seasonal distribution of several components of the Canadian Forest Fire Weather Index (FWI) System. A cluster analysis was performed on monthly normalized burnt area (NBA) series for the 1980 – 2015 period in each administrative division of the Iberian Peninsula (Portuguese districts and Spanish provinces), which revealed four pyro-regions (Northwest, North, Southwest and East) as well as significant spatial and temporal variability of NBA patterns. A separate analysis for 1980 – 1997 and 1998 – 2015 revealed noteworthy changes in the border of pyro-regions caused by changes in NBA seasonal patterns in some administrative regions. The analysis of the fire weather risk distribution for 1980 – 2017 included the assessment of extreme fire weather days, defined as days with Daily Severity Rating (DSR) above the 95th percentile, for the summer fire season, and as days with Drought Code above the 95th percentile, for the winter-spring fire season. The distribution of the monthly extreme fire weather days is highly correlated with the NBA seasonal variability and explains the differences between seasonal wildfire characteristics and the recent changes in the border administrative regions. The analysis of the fire weather patterns for large wildfires disclosed that these events were linked with extreme DSR days, especially in the NW pyro-region. These findings highlight the strong link between climate variability and fire regimes in the Iberian Peninsula, and can therefore help assess the impacts of climate change and to project future burnt area patterns.

中文翻译：

---

伊比利亚半岛燃烧区时空格局与火灾天气风险的近期演变

摘要 天气是野火发生的重要驱动因素，因为它强烈影响燃料的可用性和可燃性。在地中海气候中，火灾天气的时空模式呈现高度可变性，这有助于了解变化的火灾状况。为了评估伊比利亚半岛的这种联系以及火灾天气对火灾发生率变化的作用，这项工作确定了火区，描述了这些地区的火灾状况，并将它们与加拿大森林火灾的几个组成部分的空间和季节分布进行了比较天气指数（FWI）系统。对 1980 年至 2015 年期间伊比利亚半岛每个行政区（葡萄牙地区和西班牙省份）的月度标准化燃烧面积 (NBA) 系列进行了聚类分析，这揭示了四个热区（西北、北部、西南和东部）以及 NBA 模式的显着时空变异性。对 1980-1997 年和 1998-2015 年的单独分析显示，由于某些行政区域的 NBA 季节性模式的变化，烟火区边界发生了值得注意的变化。对 1980 年至 2017 年火灾天气风险分布的分析包括对极端火灾天气天数的评估，定义为每日严重等级 (DSR) 高于 95% 的天数、夏季火灾季节的天数以及干旱代码高于 95% 的天数。第 95 个百分位数，用于冬春季火灾季节。每月极端火灾天气天数的分布与 NBA 的季节性变化高度相关，并解释了季节性野火特征与边境行政区域近期变化之间的差异。对大型野火的火灾天气模式的分析表明，这些事件与极端 DSR 日有关，尤其是在西北火烧区。这些发现突出了气候变化与伊比利亚半岛火灾状况之间的密切联系，因此有助于评估气候变化的影响并预测未来的燃烧区域模式。