Abstract. Recently, many remote-sensing (RS) based datasets providing features of individual fire events from gridded global burned area products have been released. Although very promising, these datasets still lack a quantitative estimate of their accuracy with respect to historical ground-based fire databases. Here, we compared three state-of-the-art RS datasets (Fire Atlas, FRY and GlobFire) with high-quality ground databases compiled by regional fire agencies (AG) across the Southwestern Mediterranean basin (2005–2015). We assessed the spatial and temporal accuracy in estimated RS burned area (BA) and number of fires (NF) aggregated at monthly and 0.25° resolutions, considering different individual fire size thresholds ranging from 1 to 500 ha. Our results show that RS datasets were highly correlated with AG in terms of monthly BA and NF but severely underestimated both (by 38 % and 96 %, respectively) when considering all fires > 1 ha. Stronger agreement was found when increasing the fire size threshold, with fires > 100 ha denoting higher correlation and much lower error (BA 10 %; NF 35%). The agreement between RS and AG was also the highest during the warm season (May to October) in particular across the regions with greater fire activity such as the Northern Iberian Peninsula. The Fire Atlas displayed a slightly better performance, with a lower relative error, although uncertainty in gridded BA product largely outpaced uncertainties across the RS datasets. Overall, our findings suggest a reasonable agreement between RS and ground-based datasets for fires larger than 100 ha, but care is needed when examining smaller fires at regional scales.

中文翻译：

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评估整个西南地中海盆地的遥感火灾数据集的准确性

摘要。最近，已经发布了许多基于遥感（RS）的数据集，这些数据集提供了由网格化的全球燃烧区域产品产生的单个火灾事件的特征。尽管非常有前途，但相对于基于历史的地面火灾数据库，这些数据集仍缺乏对其准确性的定量估计。在这里，我们将三个最先进的RS数据集（Fire Atlas，FRY和GlobFire）与西南地中海盆地（2005-2015年）由地区消防局（AG）汇编的高质量地面数据库进行了比较。考虑到不同的单个火势阈值（范围从1到500公顷），我们评估了估计的RS燃烧面积（BA）和以每月和0.25°分辨率汇总的火灾（NF）的空间和时间准确性。我们的结果表明，在考虑所有大于1公顷的火灾时，RS数据集在每月BA和NF方面与AG高度相关，但都被严重低估了（分别降低38％和96％）。当增加火势阈值时发现更强的一致性，火势> 100 ha表示更高的相关性和更低的误差（BA 10％； NF 35％）。RS和AG之间的协议也是在暖季（5月至10月）期间达成的最高协议，尤其是在火势较大的地区（例如北伊比利亚半岛）。尽管网格BA产品的不确定性在很大程度上超过了RS数据集的不确定性，但Fire Atlas的性能略好一些，相对误差也较小。总体而言，我们的发现表明，对于大于100公顷的火灾，RS和地面数据集之间存在合理的一致性，