Juang C S, Williams A P, Abatzoglou J T, Balch J K, Hurteau M D, Moritz M A
Lamont-Doherty Earth Observatory of Columbia University Palisades NY USA.
Department of Earth and Environmental Sciences Columbia University New York NY USA.
Geophys Res Lett. 2022 Mar 16;49(5):e2021GL097131. doi: 10.1029/2021GL097131. Epub 2022 Mar 8.
Annual forest area burned (AFAB) in the western United States (US) has increased as a positive exponential function of rising aridity in recent decades. This non-linear response has important implications for AFAB in a changing climate, yet the cause of the exponential AFAB-aridity relationship has not been given rigorous attention. We investigated the exponential AFAB-aridity relationship in western US forests using a new 1984-2019 database of fire events and 2001-2020 satellite-based records of daily fire growth. While forest-fire frequency and duration grow linearly with aridity, the exponential AFAB-aridity relationship results from the exponential growth rates of individual fires. Larger fires generally have more potential for growth due to more extensive firelines. Thus, forces that promote fire growth, such as aridification, have more potent effects on larger fires. As aridity increases linearly, the potential for growth of large fires accelerates, leading to exponential increases in AFAB.
近几十年来，美国西部的年森林烧毁面积（AFAB）随着干旱加剧呈正指数函数增长。这种非线性响应对于气候变化下的AFAB具有重要意义，但AFAB与干旱之间指数关系的成因尚未得到严格关注。我们利用一个新的1984 - 2019年火灾事件数据库以及2001 - 2020年基于卫星的每日火灾增长记录，研究了美国西部森林中AFAB与干旱之间的指数关系。虽然森林火灾的频率和持续时间随干旱呈线性增长，但AFAB与干旱之间的指数关系是由单个火灾的指数增长率导致的。由于火线范围更广，较大的火灾通常具有更大的增长潜力。因此，诸如干旱化等促进火灾增长的因素对较大火灾的影响更为显著。随着干旱程度呈线性增加，大型火灾的增长潜力加速上升，导致AFAB呈指数增长。
