Investigation of global particulate nitrate from the AeroCom phase III experiment
Investigation of global particulate nitrate from the AeroCom phase III experiment
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DOI：
10.5194/acp-17-12911-2017
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发表时间：
2017-11-03
影响因子：
6.3
通讯作者：
Tsyro, Svetlana G.
中科院分区：
文献类型：
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作者：
Bian, Huisheng;Chin, Mian;Tsyro, Svetlana G.
根据参加观测与模型间气溶胶比较(AeroCom)第三阶段研究的九个模型的模拟，对全球颗粒物硝酸盐和氨气溶胶进行了评估。进行了预算分析，以了解气溶胶及其前体在模型中的典型大小、分布和多样性。为了获得对模型性能的信心，评估了全球各种观测结果，包括北美、欧洲和东亚的地面站测量的示踪剂浓度和干湿沉积，以及北半球中高纬度地区的飞机测量的示踪剂垂直分布。考虑到硝酸盐赋存的独特的化学和物理特征，我们通过考察(1)依赖于pH的NH3湿沉降；(2)硝酸盐在尘埃和海盐颗粒表面的非均相化学或包括尘埃和海盐离子的热力学平衡计算；(3)硝酸盐的粗模分数(即粗/总)，进一步考察了模型之间的相似性和差异性。结果表明，所有模式都是基于O-3-HOx-NOx-气溶胶全化学显式模拟的HNO3，其全球对流层负荷在不同模式中相差达9倍。这部分地导致了NO3-的巨大差异，其大气负荷相差高达13倍。NH3和NH4+的大气负荷分别相差17和4。在过程水平上的分析表明，大气中NO3-、NH3和NH4+负荷的巨大差异也与沉积过程有关。湿沉降似乎是决定NH3和NH4+寿命多样性的主要过程。正确计算硝酸盐的非均相化学产物对粉尘和海盐的贡献是至关重要的，因为这一过程压倒性地控制着大气中硝酸盐的产生(通常为80%)，并决定了硝酸盐气溶胶的粗模和细模分布。
An assessment of global particulate nitrate and ammonium aerosol based on simulations from nine models participating in the Aerosol Comparisons between Observations and Models (AeroCom) phase III study is presented. A budget analysis was conducted to understand the typical magnitude, distribution, and diversity of the aerosols and their precursors among the models. To gain confidence regarding model performance, the model results were evaluated with various observations globally, including ground station measurements over North America, Europe, and east Asia for tracer concentrations and dry and wet depositions, as well as with aircraft measurements in the Northern Hemisphere mid-to-high latitudes for tracer vertical distributions. Given the unique chemical and physical features of the nitrate occurrence, we further investigated the similarity and differentiation among the models by examining (1) the pH-dependent NH3 wet deposition; (2) the nitrate formation via heterogeneous chemistry on the surface of dust and sea salt particles or thermodynamic equilibrium calculation including dust and sea salt ions; and (3) the nitrate coarse-mode fraction (i.e., coarse/total). It is found that HNO3, which is simulated explicitly based on full O-3-HOx-NOx-aerosol chemistry by all models, differs by up to a factor of 9 among the models in its global tropospheric burden. This partially contributes to a large difference in NO3-, whose atmospheric burden differs by up to a factor of 13. The atmospheric burdens of NH3 and NH4+ differ by 17 and 4, respectively. Analyses at the process level show that the large diversity in atmospheric burdens of NO3-, NH3, and NH4+ is also related to deposition processes. Wet deposition seems to be the dominant process in determining the diversity in NH3 and NH4+ lifetimes. It is critical to correctly account for contributions of heterogeneous chemical production of nitrate on dust and sea salt, because this process overwhelmingly controls atmospheric nitrate production (typically > 80 %) and determines the coarse-and fine-mode distribution of nitrate aerosol.