State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China; College of Earth and Planetary Sciences, University of 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. 2022 Sep 10;838(Pt 4):156550. doi: 10.1016/j.scitotenv.2022.156550. Epub 2022 Jun 8.
Fires across the Arctic-boreal zone (ABZ) play an important role in the boreal forest succession, permafrost thaw, and the regional and global carbon cycle and climate. These fires occur mainly in summer with large interannual variability. Previous studies primarily focused on the impacts of local surface climate and tropical El Niño-Southern Oscillation (ENSO). This study, for the first time, comprehensively investigates the influence of summer leading large-scale atmospheric teleconnection patterns in the Northern Hemisphere extra-tropics on interannual variability of ABZ fires. We use correlation and regression analysis of 1997-2019 multiple satellite-based products of burned area and observed/reanalyzed climate data. Results show that eight leading teleconnection patterns significantly affect 63 ± 2 % of burned areas across the ABZ. Western North America is affected by the East Pacific/North Pacific pattern (EP/NP) and the West Pacific pattern (WP); boreal Europe by the Scandinavia pattern (SCA); eastern North America, western and central Siberia, and southeastern Siberia by the North Atlantic Oscillation (NAO); and eastern Siberia /Russian Far East by the East Atlantic pattern (EA). NAO/EA induces lower-tropospheric drier northwesterly/northerly airflow passing through the east of boreal North America/Eurasia, which decreases surface relative humidity. Other teleconnections trigger a high-pressure anomaly, forcing downward motion that suppresses cloud formation and increases solar radiation reaching the ground to warm the surface air as well as brings drier air downward to reduce surface relative humidity. The drier and/or warmer surface air can decrease fuel wetness and thus increase burned area. Our study highlights the important role of the extra-tropical teleconnection patterns on ABZ fires, which is much stronger than ENSO that was thought to control interannual variability of global fires. It also establishes a theoretical foundation for ABZ fire prediction based on extra-tropical teleconnections, and has the potential to facilitate ABZ fire prediction and management.
北极-亚北极地区（ABZ）的火灾在北方森林演替、永久冻土融化以及区域和全球碳循环和气候中起着重要作用。这些火灾主要发生在夏季，年际间变化较大。以前的研究主要集中在当地地表气候和热带厄尔尼诺-南方涛动（ENSO）的影响上。本研究首次全面调查了北半球中纬度夏季主要大气遥相关模式对 ABZ 火灾年际变化的影响。我们使用了 1997-2019 年多个基于卫星的燃烧面积产品和观测/再分析气候数据的相关和回归分析。结果表明，八个主要遥相关模式显著影响了 ABZ 地区 63±2%的燃烧面积。北美西部受东太平洋/北太平洋模式（EP/NP）和西太平洋模式（WP）影响；北欧受斯堪的纳维亚模式（SCA）影响；北美东部、西西伯利亚和中西伯利亚以及东西伯利亚东南部受北大西洋涛动（NAO）影响；东西伯利亚/俄罗斯远东受东大西洋涛动（EA）影响。NAO/EA 导致穿过北美东部和欧亚大陆的低空更干燥的西北/北风，从而降低地表相对湿度。其他遥相关模式引发高空异常，迫使向下运动，抑制云的形成，增加到达地面的太阳辐射，使地表空气变暖，并使干燥空气向下流动，从而降低地表相对湿度。更干燥和/或更温暖的地表空气可以降低燃料湿度，从而增加燃烧面积。本研究强调了中纬度遥相关模式对 ABZ 火灾的重要作用，其作用远强于被认为控制全球火灾年际变化的 ENSO。它还为基于中纬度遥相关的 ABZ 火灾预测奠定了理论基础，并有潜力促进 ABZ 火灾预测和管理。
