The ice-nucleating activity of African mineral dust in the Caribbean boundary layer
The ice-nucleating activity of African mineral dust in the Caribbean boundary layer
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DOI：
10.5194/acp-22-9663-2022
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发表时间：
2022-07-29
影响因子：
6.3
通讯作者：
Murray, Benjamin J.
中科院分区：
文献类型：
--
作者：
Harrison, Alexander D.;O'Sullivan, Daniel;Murray, Benjamin J.
非洲矿物尘埃从其来源地区被运送到数千公里之外，由于其成核冰的能力，它在地球仪周围的云冰川作用中发挥着重要作用。沙漠尘埃的冰成核活性受其矿物学的影响，其在源区和粒径之间变化很大。然而，在模型中，常常假定大气矿物尘埃的活性（以每单位表面积的活性位点表示，作为温度的函数）在地球仪上的任何地方都是相同的。在这里，我们发现，在巴巴多斯夏季海洋边界层（2017年7月和8月）采样的非洲沙漠尘埃的冰成核活性大大低于基于撒哈拉沙漠特定地点土壤或沙尘暴沉积尘埃的参数化。我们的结论是，巴巴多斯的边界层中的灰尘的活动主要是由低钾长石含量的灰尘，这是1%左右。我们认为，我们在加勒比地区采样的灰尘来自西非的一个地区（毛里塔尼亚和马里的萨赫勒地区及其周围），其长石含量比撒哈拉和萨赫勒地区的其他非洲来源低得多。
African mineral dust is transported many thousands of kilometres from its source regions, and, because of its ability to nucleate ice, it plays a major role in cloud glaciation around the globe. The ice-nucleating activity of desert dust is influenced by its mineralogy, which varies substantially between source regions and across particle sizes. However, in models it is often assumed that the activity (expressed as active sites per unit surface area as a function of temperature) of atmospheric mineral dust is the same everywhere on the globe. Here, we find that the ice-nucleating activity of African desert dust sampled in the summertime marine boundary layer of Barbados (July and August 2017) is substantially lower than parameterizations based on soil from specific locations in the Sahara or dust sedimented from dust storms. We conclude that the activity of dust in Barbados' boundary layer is primarily defined by the low K-feldspar content of the dust, which is around 1 %. We propose that the dust we sampled in the Caribbean was from a region in western Africa (in and around the Sahel in Mauritania and Mali), which has a much lower feldspar content than other African sources across the Sahara and Sahel.