Technical note: Identification of two ice-nucleating regimes for dust-related cirrus clouds based on the relationship between number concentrations of ice-nucleating particles and ice crystals
Technical note: Identification of two ice-nucleating regimes for dust-related cirrus clouds based on the relationship between number concentrations of ice-nucleating particles and ice crystals
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DOI：
10.5194/acp-22-13067-2022
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发表时间：
2022-10
影响因子：
6.3
通讯作者：
Yun He;Zhenping Yin;Fuchao Liu;F. Yi
中科院分区：
文献类型：
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作者：
Yun He;Zhenping Yin;Fuchao Liu;F. Yi
抽象的。每年大量的尘埃气溶胶被提升到对流层上部，并通过充当有效的冰核在卷云形成中发挥重要作用。然而，在全球范围内，与沙尘有关的卷云中的非均质成核和自发均质成核的相对重要性仍然没有得到很好的评价。在这里，基于星载观测，我们提出了一种方法来确定两个冰成核制度的尘埃相关卷云，即，(1)非均质成核的唯一存在和（2）非均质和均质成核之间的竞争，通过表征使用偏振激光雷达PHOtometer Networking（POLIPHON）方法从具有正交偏振的云-气溶胶激光雷达（CALIOP）计算的尘冰成核颗粒浓度（INPC）与来自DARDAR（激光雷达）数据集的云中冰晶数浓度（ICNC）之间的关系。文中给出了两个典型的中国中部卷云个例。在第一种情况下，一系列卷云的上部（靠近云顶）成功地实现了INPC-ICNC闭合，这意味着只发生非均质成核，而卷云的下部显示出非均质和均质成核之间可能的竞争。在第二种情况下，ICNC卷云显着超过尘埃INPC在附近的一个数量级以上，揭示了除了灰尘诱导的异相成核，均匀成核也参与了冰的形成，并产生额外的冰晶。所提出的识别方法有望应用于评估对流层上部沙尘对全球卷云形成的影响，以及调查卷云变薄在抵消气候变暖方面的潜在积极作用。
Abstract. Large amounts of dust aerosols are lifted to the upper troposphere every year and play a major role in cirrus formation by acting as efficient ice nuclei. However, the relative importance of heterogeneous nucleation and spontaneous homogenous nucleation in dust-related cirrus clouds is still not well evaluated globally. Here, based on spaceborne observations, we propose a method to identify two ice-nucleating regimes of dust-related cirrus clouds, i.e., (1) the sole presence of heterogeneous nucleation and (2) competition between heterogeneous and homogeneous nucleation, by characterizing the relationship between dust ice-nucleating particle concentrations (INPCs) calculated from the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) using the POlarization LIdar PHOtometer Networking (POLIPHON) method and in-cloud ice crystal number concentration (ICNC) from the DARDAR (lidar–radar) dataset. Two typical cirrus cases over central China are shown as a demonstration. In the first case, the upper part (near the cloud top) of a series of cirrus clouds successfully realized the INPC–ICNC closure, meaning that solely heterogeneous nucleation takes place, while the lower part of cirrus clouds showed the possible competition between heterogeneous and homogeneous nucleation. In the second case, the ICNCs in the cirrus cloud dramatically exceeded the dust INPCs in the vicinity by more than an order of magnitude, revealing that besides dust-induced heterogeneous nucleation, homogeneous nucleation also participated in ice formation and produced additional ice crystals. The proposed identification method is anticipated to apply in the evaluation of the influence of upper-troposphere dust on global cirrus formation and the investigation of the potential positive role of cirrus cloud thinning in the offset of climate warming.