Linking the Different Diameter Types of Aspherical Desert Dust Indicates That Models Underestimate Coarse Dust Emission
Linking the Different Diameter Types of Aspherical Desert Dust Indicates That Models Underestimate Coarse Dust Emission
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DOI：
10.1029/2020gl092054
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发表时间：
2020-11
影响因子：
5.2
通讯作者：
Yue Huang;A. Adebiyi;P. Formenti;J. Kok
中科院分区：
文献类型：
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作者：
Yue Huang;A. Adebiyi;P. Formenti;J. Kok
沙尘气溶胶尺寸的测量通常获得光学或投影面积等效直径，而沙尘影响的模型计算则使用几何或空气动力学直径。因此，四种直径类型之间的准确转换至关重要。然而，大多数目前的转换假设尘埃是球形的，即使许多研究表明尘埃是高度非球面的。在这里，我们获得了不同直径类型之间的转换，占尘埃非球面。我们的转换表明，光学粒子计数器低估了灰尘的几何直径（Dgeo）在粗尺寸。我们进一步使用的直径转换，以获得一致的观测约束的大小分布的排放尘埃。这一观测约束比全球气溶胶模式中使用的参数化更粗糙，后者将10 ≤ Dgeo ≤ 20 μm范围内的尘埃排放量低估了100倍，并且通常无法解释Dgeo ≥ 20 μm的大量尘埃排放。我们的研究结果表明，模型大大低估了粗粉尘排放。
Measurements of dust aerosol size usually obtain the optical or projected area‐equivalent diameters, whereas model calculations of dust impacts use the geometric or aerodynamic diameters. Accurate conversions between the four diameter types are thus critical. However, most current conversions assume dust is spherical, even though numerous studies show that dust is highly aspherical. Here, we obtain conversions between different diameter types that account for dust asphericity. Our conversions indicate that optical particle counters have underestimated dust geometric diameter (Dgeo) at coarse sizes. We further use the diameter conversions to obtain a consistent observational constraint on the size distribution of emitted dust. This observational constraint is coarser than parameterizations used in global aerosol models, which underestimate the mass of emitted dust within 10 ≤ Dgeo ≤ 20 μm by a factor of ∼2 and usually do not account for the substantial dust emissions with Dgeo ≥ 20 μm. Our findings suggest that models substantially underestimate coarse dust emission.