African biomass burning plumes over the Atlantic: aircraft based measurements and implications for H2SO4 and HNO3 mediated smoke particle activation
African biomass burning plumes over the Atlantic: aircraft based measurements and implications for H2SO4 and HNO3 mediated smoke particle activation
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DOI：
10.5194/acp-11-3211-2011
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发表时间：
2011-04
影响因子：
6.3
通讯作者：
V. Fiedler;F. Arnold;S. Ludmann;A. Minikin;L. Pirjola;A. Dörnbrack;H. Schlager
中科院分区：
文献类型：
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作者：
V. Fiedler;F. Arnold;S. Ludmann;A. Minikin;L. Pirjola;A. Dörnbrack;H. Schlager
抽象。在东大西洋（几内亚湾）上空的两个老化的生物质燃烧（BB）羽流中进行了痕量气体和气溶胶粒子的空中测量。烟羽起源于南半球非洲稀树草原带的BB。在我们测量当天（2006年8月13日），羽流的年龄约为10天，分别位于对流层中部（MT）3900-5500 m高度和对流层上部（UT）10800 - 11200 m高度。MT羽流可能是由干对流抬升的，UT羽流可能是由湿对流抬升的。在污染更严重的MT-羽流中，许多测量的痕量物质的丰度明显升高，特别是SO2（高达1400 pmol mol−1），HNO 3（5000-8000 pmol mol−1）和直径大于270 nm（高达2000 cm−3）的烟雾颗粒。我们的MT-羽测量表明，由BB释放的SO2没有经历沉积和云过程的显着损失，而是经历了OH诱导转化为气相硫酸。相比之下，一个显着的一部分释放的NOy经历了损失，最有可能作为HNO 3的沉积。在UT-羽，损失的NOy和SO2相比，MT-羽更明显，可能是由于云的过程。建立在我们的测量和相应的模型模拟，我们已经研究了微量气体的转换，在老化和稀释羽流和烟雾粒子的处理和激活中的作用。重点放在硫酸和硝酸铵的形成，以及它们对烟雾颗粒的活化电位的影响。我们的模型模拟显示，8月13日之后，较低的羽流穿越大西洋，下降到1300米，此后再次上升。在穿越大西洋的过程中，烟雾颗粒的可溶性质量分数和它们的平均直径增加到足以使处理过的烟雾颗粒在只有约0.04%的非常低的水蒸气过饱和度下就已经充当水蒸气凝结核。因此，老化的烟雾粒子有可能成为海洋云形成过程中的水汽凝结核。
Abstract. Airborne measurements of trace gases and aerosol particles have been made in two aged biomass burning (BB) plumes over the East Atlantic (Gulf of Guinea). The plumes originated from BB in the Southern-Hemisphere African savanna belt. On the day of our measurements (13 August 2006), the plumes had ages of about 10 days and were respectively located in the middle troposphere (MT) at 3900–5500 m altitude and in the upper troposphere (UT) at 10 800–11 200 m. Probably, the MT plume was lifted by dry convection and the UT plume was lifted by wet convection. In the more polluted MT-plume, numerous measured trace species had markedly elevated abundances, particularly SO2 (up to 1400 pmol mol−1), HNO3 (5000–8000 pmol mol−1) and smoke particles with diameters larger than 270 nm (up to 2000 cm−3). Our MT-plume measurements indicate that SO2 released by BB had not experienced significant loss by deposition and cloud processes but rather had experienced OH-induced conversion to gas-phase sulfuric acid. By contrast, a significant fraction of the released NOy had experienced loss, most likely as HNO3 by deposition. In the UT-plume, loss of NOy and SO2 was more pronounced compared to the MT-plume, probably due to cloud processes. Building on our measurements and accompanying model simulations, we have investigated trace gas transformations in the ageing and diluting plumes and their role in smoke particle processing and activation. Emphasis was placed upon the formation of sulfuric acid and ammonium nitrate, and their influence on the activation potential of smoke particles. Our model simulations reveal that, after 13 August, the lower plume traveled across the Atlantic and descended to 1300 m and hereafter ascended again. During the travel across the Atlantic, the soluble mass fraction of smoke particles and their mean diameter increased sufficiently to allow the processed smoke particles to act as water vapor condensation nuclei already at very low water vapor supersaturations of only about 0.04%. Thereby, aged smoke particles had developed a potential to act as water vapor condensation nuclei in the formation of maritime clouds.