Climate Models and Remote Sensing Retrievals Neglect Substantial Desert Dust Asphericity
Climate Models and Remote Sensing Retrievals Neglect Substantial Desert Dust Asphericity
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DOI：
10.1029/2019gl086592
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发表时间：
2020-03-28
影响因子：
5.2
通讯作者：
Jokinen, Olli
中科院分区：
文献类型：
--
作者：
Huang, Yue;Kok, Jasper F.;Jokinen, Olli
气候模式和遥感反演一般假设沙尘气溶胶是球形或类球形的。然而，测量结果表明，尘埃气溶胶从球形和类球形的形状，颗粒的长宽比（纵横比）和高宽比（高宽比）的比例偏离大幅度从一。在这里，我们通过汇编几十个测量纵横比和高宽比的地球仪来量化尘埃的非球面性。我们发现，平均长度是5倍大于高度，气候模型和遥感反演低估了这种非球面性的一个因素，类似于3-5。汇编的测量结果进一步表明，北非尘埃在传输过程中变得更加非球面，而亚洲尘埃可能变得不那么非球面。我们得到了全球平均的形状分布，从中我们发现，占尘埃非球面增加重力沉降寿命类似于20%。寿命的增加有助于解释模型对粗尘输送的低估。
Climate models and remote sensing retrievals generally assume that dust aerosols are spherical or spheroidal. However, measurements show that dust aerosols deviate substantially from spherical and spheroidal shapes, as ratios of particle length to width (the aspect ratio) and height to width (height-to-width ratio) deviate substantially from unity. Here, we quantify dust asphericity by compiling dozens of measurements of aspect ratio and height-to-width ratio across the globe. We find that the length is on average 5 times larger than the height and that climate models and remote sensing retrievals underestimate this asphericity by a factor of similar to 3-5. Compiled measurements further suggest that North African dust becomes more aspherical during transport, whereas Asian dust might become less aspherical. We obtain globally-averaged shape distributions, from which we find that accounting for dust asphericity increases gravitational settling lifetime by similar to 20%. This increased lifetime helps explain the underestimation of coarse dust transport by models.