Canadian Aerosol Module (CAM): A size-segregated simulation of atmospheric aerosol processes for climate and air quality models 2. Global sea-salt aerosol and its budgets
Canadian Aerosol Module (CAM): A size-segregated simulation of atmospheric aerosol processes for climate and air quality models 2. Global sea-salt aerosol and its budgets
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DOI：
10.1029/2001jd002004
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发表时间：
2002-12
影响因子：
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通讯作者：
S. Gong;L. Barrie;M. Lazare
中科院分区：
文献类型：
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作者：
S. Gong;L. Barrie;M. Lazare
[1] 使用加拿大气溶胶模块 (CAM)，将尺寸分离的海盐气溶胶作为动态成分纳入第三代加拿大大气环流模型 (GCMIII)。使用 12 箱截面模型来模拟表面依赖于风的海盐气溶胶的生成、扩散和平流输送，以及作为颗粒尺寸函数的湿和干去除。模型预测的大气海盐浓度对风速的依赖性弱于 u3.41 对海盐排放的依赖性，但仍然很重要。通过将 GCMIII 地面风与欧洲中期天气预报中心重新分析的风进行比较，确定了模拟地面海洋风的全球平均偏差为 18%。考虑到这一点，进行了两年的模拟来研究大气海盐循环。季节平均模型预测与 24 个海洋观测站观测到的海盐质量浓度的比较具有合理的一致性（通常优于 2 倍）。全球每年的海盐通量估计为 1.01 × 1013 kg，其中约 32% 来自北半球，98% 为超微米颗粒。尽管排放到大气中的半径大于0.2微米的亚微米海盐颗粒仅占全球总排放量的2%，但它们对海洋大气中的背景气溶胶质量和数量浓度有显着影响。亚微米海盐气溶胶对公海大气的总光学深度有很大贡献。它们占地表空气中海盐总量的 5-15%，在 700 hPa 时占 20%。海洋上空海盐气溶胶的全球质量平均干直径在表面为 2.8 μm，在对流层中层为 1.9 μm。 10 月至次年 3 月，南半球四十度左右和北部海洋上空的浓度最高。海盐气溶胶的停留时间根据尺寸、垂直分散和去除过程而变化很大。 7.7μm和0.4μm颗粒在海洋边界层的平均停留时间分别为0.3-10小时和80-360小时。
[1] Size-segregated sea-salt aerosols were included as dynamic constituents in the third generation of the Canadian general circulation model (GCMIII) using the Canadian Aerosol Module (CAM). A 12-bin sectional model was used to simulate wind-dependent sea-salt aerosol generation at the surface, diffusive, and advective transports, as well as wet and dry removals as a function of particle size. The dependence of model-predicted atmospheric sea-salt concentration on wind speed is weaker than the u3.41 dependence of sea-salt emissions but nevertheless still significant. A comparison of GCMIII surface winds with European Centre for Medium-Range Weather Forecasting reanalyzed winds was used to identify a globally averaged bias of modeled surface marine winds of 18%. After taking this into account, two-year simulations were performed to study the atmospheric sea-salt cycle. Comparisons of seasonal mean model predictions with observed sea-salt mass concentrations at 24 marine observatories were in reasonable agreement (generally better than a factor of 2). The annual global sea-salt flux is estimated to be 1.01 × 1013 kg with ∼32% from the Northern Hemisphere and with 98% in supermicron particles. Although emissions to the atmosphere of submicron sea-salt particles larger than 0.2 μm radius make up only 2% of the total global emissions, they contribute significantly to the background aerosol mass and number concentrations in the marine atmosphere. Submicron sea-salt aerosols contribute substantially to the total optical depth of the atmosphere over the open oceans. They account for 5–15% of total sea-salt mass in air at the surface and 20% at 700 hPa. The global mass mean dry diameter of sea-salt aerosols over oceans is 2.8 μm at the surface and 1.9 μm in the midtroposphere. Concentrations are highest in the roaring forties of the Southern Hemisphere and over the northern oceans from October to March. Residence times of sea-salt aerosols were highly variable depending on size, vertical dispersion, and removal processes. The mean residence time for 7.7 μm and 0.4 μm particles in the marine boundary layer were in the range 0.3–10 hours and 80–360 hours, respectively.