Black carbon physical and optical properties across northern India during pre-monsoon and monsoon seasons
Black carbon physical and optical properties across northern India during pre-monsoon and monsoon seasons
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DOI：
10.5194/acp-19-13079-2019
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发表时间：
2019-06
影响因子：
6.3
通讯作者：
James Brooks;Dantong Liu;James D. Allan;P. I. Williams;J. Haywood;Ellie Highwood;S. K. Kompalli;S. S. Babu-S.;S. Satheesh;Andrew G. Turner;H. Coe
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文献类型：
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作者：
James Brooks;Dantong Liu;James D. Allan;P. I. Williams;J. Haywood;Ellie Highwood;S. K. Kompalli;S. S. Babu-S.;S. Satheesh;Andrew G. Turner;H. Coe
抽象。众所周知，黑碳（BC）对气候和人类健康都有重大影响，因此具有全球重要性，特别是在靠近大量人口的地区。使用单粒子烟尘光度计（SP2）的尺寸分辨的混合状态的含BC的颗粒的特征。该研究的重点是印度-恒河平原（IGP）在前季风和季风季节。所提供的数据来自英国机载大气测量设施BAe-146研究飞机，这些飞机在2016年季风前（6月11日和12日）和季风季节（6月30日至7月11日）进行了飞行。在IGP，BC质量浓度（1.95 µg m−3）高于印度西北部（1.50 µg m−3）和印度东北部（0.70 µg m−3）。在整个印度北方，记录了两种不同的BC模式;一种是小BC颗粒模式（核心直径<0.16 µm，涂层厚度<50 nm），另一种是中等涂层BC模式（核心直径<0.22 µm，涂层厚度为50-200 nm）。IGP和印度东北部的位置表现出适度涂层的黑碳颗粒增强涂层厚度，核心尺寸，质量吸收截面和散射增强值相比，低得多的值存在于西北部。与边界层相比，涂层厚度和质量吸收截面随高度增加（13%）。随着季风到达整个地区，BC的质量浓度下降了中央IGP和东北部的位置（分别为38%和28%），而西北部的位置BC属性保持相对一致。后季风爆发，涂层厚度，核心尺寸，质量吸收截面，散射增强值都是最大的中央IGP很像前季风季节，但在印度东北部和西北部大大减少。通过大气柱的质量吸收截面的增加仍然存在于季风期间的西北部和中部IGP的位置，但在东北部，由于缺乏远程传输气溶胶高空。在印度-恒河平原和印度东北部，在前季风和季风季节，固体燃料（木材燃烧）排放量在具有中等涂层颗粒的BC中占最大比例。然而，随着季风在东北部的发展，有一个切换到小的未涂覆的BC颗粒指示交通排放，但固体燃料排放仍然在IGP进入季风。在西北部的两个季节中，交通排放物构成了BC颗粒的最大比例。我们的研究结果将被证明是重要的BC的物理和光学特性的更好的理解，具有重要的后果，为大气辐射强迫的含BC粒子。研究结果还将有助于限制区域气溶胶模型的各种应用，如天基遥感，化学运输建模，空气质量和BC源和排放清单。
Abstract. Black carbon (BC) is known to have major impacts on both climate and human health and is therefore of global importance, particularly in regions close to large populations that have strong sources. The size-resolved mixing state of BC-containing particles was characterised using a single-particle soot photometer (SP2). The study focusses on the Indo-Gangetic Plain (IGP) during the pre-monsoon and monsoon seasons. Data presented are from the UK Facility for Airborne Atmospheric Measurements BAe-146 research aircraft that performed flights during the pre-monsoon (11 and 12 June) and monsoon (30 June to 11 July) seasons of 2016. Over the IGP, BC mass concentrations were greater (1.95 µg m−3) compared to north-west India (1.50 µg m−3) and north-east India (0.70 µg m−3) during the pre-monsoon season. Across northern India, two distinct BC modes were recorded; a mode of small BC particles (core diameter <0.16 µm and coating thickness <50 nm) and a mode of moderately coated BC (core diameter <0.22 µm and coating thickness of 50–200 nm). The IGP and north-east India locations exhibited moderately coated black carbon particles with enhanced coating thicknesses, core sizes, mass absorption cross sections, and scattering enhancement values compared to much lower values present in the north-west. The coating thickness and mass absorption cross section increased with altitude (13 %) compared to those in the boundary layer. As the monsoon arrived across the region, mass concentration of BC decreased over the central IGP and north-east locations (38 % and 28 % respectively), whereas for the north-west location BC properties remained relatively consistent. Post-monsoon onset, the coating thickness, core size, mass absorption cross section, and scattering enhancement values were all greatest over the central IGP much like the pre-monsoon season but were considerably reduced over both north-east and north-west India. Increases in mass absorption cross section through the atmospheric column were still present during the monsoon for the north-west and central IGP locations, but less so over the north-east due to lack of long-range transport aerosol aloft. Across the Indo-Gangetic Plain and north-east India during the pre-monsoon and monsoon seasons, solid-fuel (wood burning) emissions form the greatest proportion of BC with moderately coated particles. However, as the monsoon develops in the north-east there was a switch to small uncoated BC particles indicative of traffic emissions, but the solid-fuel emissions remained in the IGP into the monsoon. For both seasons in the north-west, traffic emissions form the greatest proportion of BC particles. Our findings will prove important for greater understanding of the BC physical and optical properties, with important consequences for the atmospheric radiative forcing of BC-containing particles. The findings will also help constrain the regional aerosol models for a variety of applications such as space-based remote sensing, chemistry transport modelling, air quality, and BC source and emission inventories.