Ice crystal number concentration estimates from lidar–radar satellite remote sensing – Part 1: Method and evaluation
Ice crystal number concentration estimates from lidar–radar satellite remote sensing – Part 1: Method and evaluation
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DOI：
10.5194/acp-18-14327-2018
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发表时间：
2017-03
影响因子：
6.3
通讯作者：
O. Sourdeval;E. Gryspeerdt;M. Krämer;T. Goren;J. Delanoë;A. Afchine;F. Hemmer;J. Quaas
中科院分区：
文献类型：
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作者：
O. Sourdeval;E. Gryspeerdt;M. Krämer;T. Goren;J. Delanoë;A. Afchine;F. Hemmer;J. Quaas
抽象的。云粒子数浓度是理解气溶胶-云相互作用和在气候和数值天气预报模式中描述云的关键量。与液态云的最新进展相反，关于冰晶数浓度（Ni）的观测限制很少。本研究探讨如何结合激光雷达测量可以用来提供卫星估计镍，使用的方法，约束矩的参数化粒度分布（PSD）。可操作的激光雷达-雷达（DARDAR）产品作为这种方法的现有基础，其重点是温度Tc<-30 ° C的冰云。理论上的考虑证明了准确的镍检索的能力，除了在小晶体中的浓度可能的偏差，当Tc =-50 ° C时，由于在目前的方法中的单峰PSD形状的假设。这是通过卫星估计一致的原位测量，这也证明了足够的灵敏度激光雷达观测镍比较验证。根据这些结果，卫星估计镍的情况下进行评估的案例研究和初步的气候分析的基础上，10年的全球数据。尽管缺乏其他大规模的参考，这一评价显示了合理的物理一致性，在镍的空间分布格局。值得注意的是，镍的增加被发现朝向冷的温度，更重要的是，在存在强烈的上升气流，如与对流或地形隆起。这种方法的进一步评估和改进是必要的，虽然这些结果已经构成了第一个令人鼓舞的一步，大规模的观测约束镍。本系列的第2部分使用这个新的数据集来检查Ni上的控件。
Abstract. The number concentration of cloud particles is a key quantity for understanding aerosol–cloud interactions and describing clouds in climate and numerical weather prediction models. In contrast with recent advances for liquid clouds, few observational constraints exist regarding the ice crystal number concentration (Ni). This study investigates how combined lidar–radar measurements can be used to provide satellite estimates of Ni, using a methodology that constrains moments of a parameterized particle size distribution (PSD). The operational liDAR–raDAR (DARDAR) product serves as an existing base for this method, which focuses on ice clouds with temperatures Tc<-30 ∘C. Theoretical considerations demonstrate the capability for accurate retrievals of Ni, apart from a possible bias in the concentration in small crystals when Tc≳−50 ∘C, due to the assumption of a monomodal PSD shape in the current method. This is verified via a comparison of satellite estimates to coincident in situ measurements, which additionally demonstrates the sufficient sensitivity of lidar–radar observations to Ni. Following these results, satellite estimates of Ni are evaluated in the context of a case study and a preliminary climatological analysis based on 10 years of global data. Despite a lack of other large-scale references, this evaluation shows a reasonable physical consistency in Ni spatial distribution patterns. Notably, increases in Ni are found towards cold temperatures and, more significantly, in the presence of strong updrafts, such as those related to convective or orographic uplifts. Further evaluation and improvement of this method are necessary, although these results already constitute a first encouraging step towards large-scale observational constraints for Ni. Part 2 of this series uses this new dataset to examine the controls on Ni.