State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100191, China.
Sci Total Environ. 2023 Jan 20;857(Pt 1):159232. doi: 10.1016/j.scitotenv.2022.159232. Epub 2022 Oct 5.
Limited by the scarcity of in situ vertical observation data, the influences of biomass burning in Southeast Asia on major atmospheric carbonaceous compositions in downwind regions have not been thoroughly studied. In this study, aircraft observations were performed to obtain high time-resolved in situ vertical distributions of black carbon (BC) as well as carbon monoxide (CO) and carbon dioxide (CO). Four types of profiles were revealed: Mode I (from 2000 to 3000 m, the BC, CO and CO concentrations were enhanced), Mode II (with increasing altitude, the BC, CO and CO concentrations almost decreased), Mode III (inhomogeneous vertical BC, CO and CO profiles with BC peaks were observed from 2500 to 3000 m) and Mode IV (the BC, CO and CO concentrations increased above 1500 m). Furthermore, simulations were conducted to calculate radiative forcing (RF) caused by BC and study the heating rate (HR) of BC in combination with the vertical BC profiles. A larger BC distribution in the atmosphere resulted in a sharp RF change from negative to positive values, imposing a nonnegligible influence on the atmospheric temperature profile, with maximum HR values ranging from 0.4 to 5.8 K/day. The values of the absorption Ångström exponent (AAE) were 1.46 ± 0.11 and 1.48 ± 0.17 at altitudes from 1000 to 2000 and 2000-3000 m, respectively. The average BC light absorption coefficient at the 370 nm wavelength (α ) accounted for 50.3 %-76.8 % of the α , while the brown carbon (BrC) light absorption coefficient at the 370 nm wavelength (α ) contributed 23.2 %-49.7 % to the α at altitudes of 1000-2000 m. At altitudes of 2000-3000 m, α and α contributed 43.8 %-88.2 % and 11.8 %-56.2 % to the α , respectively. These findings show that calculations that consider the surface BC concentration but ignore the vertical BC distribution could result in massive uncertainties in estimating the RF and HR caused by BC. This study helped achieve a deeper understanding of the influences of biomass burning over the region of Southeast Asia on the profiles of atmospheric carbonaceous compositions and atmospheric BC absorption and its warming effect.
受限于原位垂直观测数据的稀缺，生物质燃烧对下风区主要大气含碳成分的影响尚未得到充分研究。本研究通过飞机观测获得了黑碳（BC）以及一氧化碳（CO）和二氧化碳（CO）的高时间分辨率原位垂直分布。揭示了四种类型的廓线：模式 I（从 2000 米到 3000 米，BC、CO 和 CO 浓度增强）、模式 II（随着海拔升高，BC、CO 和 CO 浓度几乎降低）、模式 III（BC、CO 和 CO 廓线不均匀，在 2500 米到 3000 米之间观察到 BC 峰值）和模式 IV（BC、CO 和 CO 浓度在 1500 米以上增加）。此外，还进行了模拟计算，以计算由 BC 引起的辐射强迫（RF），并结合垂直 BC 廓线研究 BC 的加热率（HR）。大气中更大的 BC 分布导致 RF 从负值急剧变为正值，对大气温度廓线产生不可忽视的影响，最大 HR 值范围为 0.4 至 5.8 K/天。在 1000 米至 2000 米和 2000 米至 3000 米的高度，吸收 Ångström 指数（AAE）的值分别为 1.46 ± 0.11 和 1.48 ± 0.17。在 370nm 波长处的 BC 光吸收系数（α ）占α 的 50.3%-76.8%，而在 1000-2000 米高度处的 BrC（棕色碳）在 370nm 波长处的光吸收系数（α ）占α 的 23.2%-49.7%。在 2000-3000 米的高度，α 和α 分别占α 的 43.8%-88.2%和 11.8%-56.2%。这些发现表明，在估算 BC 引起的 RF 和 HR 时，如果只考虑地表 BC 浓度而忽略垂直 BC 分布，可能会导致大量不确定性。本研究有助于更深入地了解东南亚地区生物质燃烧对大气含碳成分廓线和大气 BC 吸收及其增温效应的影响。
