Deactivation of ice nuclei due to atmospherically relevant surface coatings
Deactivation of ice nuclei due to atmospherically relevant surface coatings
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DOI：
10.1088/1748-9326/4/4/044013
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发表时间：
2009-10-01
影响因子：
6.7
通讯作者：
Murphy, Daniel M.
中科院分区：
文献类型：
--
作者：
Cziczo, Daniel J.;Froyd, Karl D.;Murphy, Daniel M.
在位于德国卡尔斯鲁厄研究中心的大气气溶胶相互作用和动力学(AIDA)小室中，测定了替代大气冰核的亚利桑那州测试尘埃(ATD)和伊利石粘土的成冰特性。这项研究的目的是确定硫酸和硫酸铵涂层对这些矿物粉尘替代品在颗粒实际竞争水蒸气的环境中成核冰的能力的影响。在所考虑的所有温度下，从-20到-45摄氏度，被涂层的ATD颗粒比相同的未被涂层的颗粒需要更高的饱和度。涂层颗粒的冻结通常需要接近于仅对涂层材料的水溶液进行均匀冻结的饱和度。对伊利石的影响不那么明显，尽管涂层的存在一直提高了结冰所需的饱和度或降低了结冰所需的温度。对单个颗粒水平上的冰残留物的分析表明，与后来在膨胀过程中冻结的颗粒相比，第一个冻结的涂层颗粒的涂层更薄或不完整。这一观察结果突出了验证涂层性能的必要性，因为一组涂层气雾剂的均质性的假设可能是不正确的。冻结饱和率的增加表明，硫酸盐的气相吸收--其中很大一部分是人为排放--将降低大气冰核的冰和混合相云的形成潜力。
The ice nucleation characteristics of Arizona test dust (ATD) and illite clay, surrogates for atmospheric ice nuclei, have been determined at the Aerosol Interactions and Dynamics in the Atmosphere (AIDA) chamber located at the Research Center Karlsruhe in Germany. The objective of this research was to determine the effect of sulfuric acid and ammonium sulfate coatings on the ability of these mineral dust surrogates to nucleate ice in an environment where particles realistically compete for water vapor. Coated ATD particles required higher saturations at all temperatures considered, from -20 to -45 degrees C, than did identical uncoated particles. Freezing of coated particles often required saturations approaching those for the homogeneous freezing of aqueous solutions of the coating material alone. Less pronounced effects were found for illite, although the presence of a coating consistently increased the saturation or decreased the temperature required for ice formation. Analysis of ice residue at the single particle level suggests that the first coated particles to freeze had thinner or incomplete coatings when compared to particles that froze later in the expansion. This observation highlights a need to verify coating properties since an assumption of homogeneity of a group of coated aerosols may be incorrect. The increase in saturation ratio for freezing suggests that gas-phase uptake of sulfates, a large fraction of which are due to anthropogenic emissions, will reduce the ice and mixed-phase cloud formation potential of atmospheric ice nuclei.