Lin Lin, Liu Xiaohong, Zhao Xi, Shan Yunpeng, Ke Ziming, Lyu Kai, Bowman Kenneth P
Department of Atmospheric Sciences, Texas A&M University, College Station, TX, USA.
Argonne National Laboratory, Lemont, IL, USA.
Sci Adv. 2025 May 9;11(19):eads0572. doi: 10.1126/sciadv.ads0572.
The formation of ice crystals in the atmosphere strongly affects cloud properties and climate. While volcanic ash (VA) has been shown to nucleate ice crystals efficiently in laboratory settings, its importance for ice formation in the atmosphere remains elusive. Here, we show evidence of cirrus modification by volcanic eruptions through ice nucleation on VA, revealed by abrupt changes in cirrus properties following volcanic eruptions based on satellite measurements. The distinct changes captured are a phenomenal decrease in number, an increase in size of ice crystals in cirrus clouds, and an increase in cirrus occurrences after ash-rich volcanic eruptions. Conversely, no such changes were detected following the ash-poor eruption. We propose a cirrus formation mechanism where VA nucleates ice heterogeneously, suppressing homogeneous freezing and resulting in fewer but larger ice crystals. This suppression of homogeneous freezing by VA is supported by process-level cloud microphysical simulations. Our findings advance the understanding of aerosol-ice cloud interactions and illuminate cirrus geoengineering.
大气中冰晶的形成强烈影响云的特性和气候。虽然在实验室环境中已表明火山灰（VA）能有效地使冰晶成核，但其对大气中冰形成的重要性仍不明确。在此，我们通过卫星测量发现，火山喷发后卷云特性的突然变化揭示了火山喷发通过火山灰上的冰核作用对卷云产生的影响。所捕获的明显变化包括数量显著减少、卷云中冰晶尺寸增大以及富含火山灰的火山喷发后卷云出现频率增加。相反，在火山灰含量低的喷发后未检测到此类变化。我们提出一种卷云形成机制，即火山灰异质成核使冰形成，抑制均匀冻结，从而导致冰晶数量减少但尺寸增大。这种火山灰对均匀冻结的抑制作用得到了过程级云微物理模拟的支持。我们的研究结果增进了对气溶胶 - 冰云相互作用的理解，并为卷云地球工程提供了启示。
