International Center for Climate and Environment Sciences, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China.
State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China.
Sci Total Environ. 2021 Nov 10;794:148718. doi: 10.1016/j.scitotenv.2021.148718. Epub 2021 Jun 26.
Amazonia experienced unusually devastating fires in August 2019, leading to huge regional and global environmental and economic losses. The increase in fires has been largely attributed to anthropogenic deforestation, but anomalous climate conditions could also have contributed. This study investigates the climate influence on Amazonia fires in August 2019 and underlying mechanisms, based on statistical correlation and multiple linear regression analyses of 2001-2019 satellite-based fire products and multiple observational or reanalyzed climate datasets. Positive fire anomalies in August 2019 were mainly located in southern Amazonia. These anomalies were mainly driven by low precipitation and relative humidity, which increased fuel dryness and contributed to 38.9 ± 9.5% of the 2019 anomaly in pyrogenic carbon emissions over the southern Amazonia. The dry conditions were associated with southerly wind anomalies over southern Amazonia that suppressed the climatological southward transport of water vapor originating from the Atlantic. The southerly wind anomalies were caused by the combination of a Gill-type cyclonic response to the warmer North Atlantic sea surface temperature (SST), and enhancement of the Walker and Hadley circulations over South America due to the colder SST in the eastern Pacific, and a mid-latitude wave train triggered by the warmer condition in the western Indian Ocean. Our study highlights, for the first time, the important role of Indian Ocean SST for fires in Amazonia. It also reveals how cold SST anomalies in the tropical eastern Pacific link the warm phase of the El Niño-Southern Oscillation (ENSO) in the preceding December-January to the dry-season fires in Amazonia. Our findings can develop theoretical basis of global tropical SST-based fire prediction, and have potential to improve prediction skill of extreme fires in Amazonia and thus to take steps to mitigate their impacts which is urgency given that dry conditions led to the extreme fires are becoming common in Amazonia.
2019 年 8 月，亚马逊地区经历了异常严重的火灾，导致了巨大的区域和全球环境及经济损失。火灾的增加主要归因于人为森林砍伐，但异常的气候条件也可能起到了作用。本研究利用基于卫星的火灾产品及多种观测或再分析气候数据集，通过 2001-2019 年的统计相关和多元线性回归分析，研究了 2019 年 8 月亚马逊地区火灾的气候影响及其潜在机制。2019 年 8 月，亚马逊地区南部的火灾异常主要呈正相关。这些异常主要是由低降水和相对湿度引起的，增加了燃料的干燥度，导致南部亚马逊地区的燃烧碳排放量异常增加了 38.9±9.5%。干燥的条件与亚马逊南部的南风异常有关，南风异常抑制了大西洋水汽的向南输送，从而导致了火灾异常。南风异常是由北大西洋海表温度（SST）变暖引起的吉尔型气旋响应以及由于东太平洋 SST 较冷导致南美的沃克和哈德利环流增强，以及由西印度洋较暖条件触发的中纬度波列共同引起的。本研究首次强调了印度洋 SST 对亚马逊地区火灾的重要作用。它还揭示了热带东太平洋的冷 SST 异常如何将 12-1 月厄尔尼诺-南方涛动（ENSO）暖相位与亚马逊旱季的火灾联系起来。我们的研究结果可以为基于全球热带 SST 的火灾预测提供理论基础，并有可能提高亚马逊地区极端火灾的预测能力，从而采取措施减轻其影响，鉴于导致极端火灾的干燥条件在亚马逊地区变得越来越普遍，这是当务之急。
