Key Laboratory of Regional Climate-Environment for Temperate East Asia (RCE-TEA), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China; State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou 570228, China.
Key Laboratory of Regional Climate-Environment for Temperate East Asia (RCE-TEA), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China; University of Chinese Academy of Sciences, Beijing, China.
Sci Total Environ. 2022 Oct 10;842:156949. doi: 10.1016/j.scitotenv.2022.156949. Epub 2022 Jun 23.
Southeast Asia is one of the largest biomass burning (BB) source regions in the world. In order to promote our understanding of BB aerosol characteristics and environmental impacts, this study investigated the emission, composition, evolution, radiative effects, and feedbacks of BB aerosols from Mainland Southeast Asia during 15 March to 15 April 2019 by using an online-coupled regional chemistry/aerosol-climate model RIEMS-Chem. Model results are compared against a variety of ground and vertical observations, indicating a generally good model performance for meteorology, aerosol chemical compositions, and aerosol optical properties. It is found that BB aerosols contributed significantly to regional particulate matter (PM), accounting for up to 90 % of the near-surface PM, BC, and OC concentrations over the BB source regions of north Mainland Southeast Asia and for approximately 30-70 % over wide downwind areas including most areas of southwest China and portions of south China. At the top of atmosphere (TOA), BB aerosols exerted a positive all-sky radiative effect (DRE) up to 25 W/m over north Vietnam and south China, a negative DRE up to -10 W/m over Myanmar, western Thailand, and southwest China. Meanwhile, the indirect radiative effect (IRE) was consistently negative, with the maximum of -10 W/m over downwind areas with cloud coverage, e.g., from north Vietnam to most of south China. The subregional (95-125°E and 10-30°N) and period mean DRE and IRE at TOA were estimated to be 0.69 W/m and - 0.63 W/m, respectively, leading a total radiative effect (TRE) of 0.06 W/m at TOA. The radiative effects of BB aerosols led to decreases in sensible and latent heat fluxes, near-surface temperature, PBL height, and wind speed of 6.0 Wm, 9.0 Wm, 0.26 °C, 38.7 m, and 0.1 m/s, respectively, accompanied with an increase in RH of 1.9 %, averaged over the subregion and the study period. The accumulated precipitation during the study period was apparently reduced by BB aerosols from east Thailand to south China, with the maximum reduction up to 14 cm (exceeding 40 %) over north Vietnam and south China. TRE tended to increase mean near-surface PM and its component concentrations, with the maximum percentage increase up to 24 % over the BB source regions of north Mainland Southeast Asia, resulting from the combined effects of dynamic and chemical feedbacks. DRE generally dominated over IRE in the feedback-induced PM concentration changes.
东南亚是世界上最大的生物质燃烧（BB）源区之一。为了增进我们对 BB 气溶胶特性和环境影响的理解，本研究利用在线耦合区域化学/气溶胶气候模式 RIEMS-Chem 对 2019 年 3 月 15 日至 4 月 15 日期间来自东南亚大陆的 BB 气溶胶的排放、组成、演化、辐射效应和反馈进行了调查。模型结果与各种地面和垂直观测进行了比较，表明该模型对气象、气溶胶化学成分和气溶胶光学特性的表现总体良好。结果表明，BB 气溶胶对区域颗粒物（PM）的贡献显著，在北东南亚大陆的 BB 源区，近地表 PM、BC 和 OC 浓度的 90%以上以及包括中国西南部大部分地区和中国南部部分地区在内的下风区的 30-70%以上均由 BB 气溶胶贡献。在大气顶（TOA），BB 气溶胶的全天空辐射效应（DRE）高达 25 W/m2，在越南北部和中国南部地区上空，DRE 高达 25 W/m2，在缅甸、泰国西部和中国西南部上空，DRE 高达-10 W/m2。同时，间接辐射效应（IRE）一直为负，在有云覆盖的下风区（如从越南北部到中国大部分地区）最大可达-10 W/m2。在亚区（95-125°E 和 10-30°N）和时段平均 DRE 和 IRE 在 TOA 处估计分别为 0.69 W/m 和-0.63 W/m，导致 TOA 处总辐射效应（TRE）为 0.06 W/m。BB 气溶胶的辐射效应导致感热和潜热通量、近地表温度、边界层高度和风速分别减少 6.0 W/m、9.0 W/m、0.26°C、38.7 m 和 0.1 m/s，同时 RH 增加 1.9%，平均覆盖亚区和研究期间。来自泰国东部到中国南部的 BB 气溶胶明显减少了研究期间的累计降水量，越南北部和中国南部的最大减少量高达 14 厘米（超过 40%）。TRE 倾向于增加平均近地表 PM 及其成分浓度，在东南亚大陆的 BB 源区，最大增幅高达 24%，这是由于动力和化学反馈的综合影响。在反馈引起的 PM 浓度变化中，DRE 通常超过 IRE。
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