Normalized particle size distribution for remote sensing application
Normalized particle size distribution for remote sensing application
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DOI：
10.1002/2013jd020700
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发表时间：
2014-04
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影响因子：
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通讯作者：
J. Delanoë;A. Heymsfield;A. Protat;Aaron R. Bansemer;Robin J. Hogan
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文献类型：
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作者：
J. Delanoë;A. Heymsfield;A. Protat;Aaron R. Bansemer;Robin J. Hogan
冰粒径分布 (PSD) 是定量描述云的基础。它对于使用雷达和/或激光雷达测量的遥感检索技术的发展也至关重要。 PSD 允许将单个粒子的特征（面积、质量和散射属性）与采样体积中粒子群的特征（例如，可见消光 (σ)、冰水含量 (IWC) 和雷达反射率 (Z)）联系起来。本研究的目的是描述一种表示 PSD 的归一化技术。我们更新了一项早期研究，纳入了最近的原位测量，涵盖了温度范围在 -80°C 到 0°C 之间的各种冰云。这个新数据集还包括 IWC 的直接测量结果。我们证明可以通过体积加权直径 Dm 在尺寸空间中缩放 PSD，并通过截距参数 N0* 在浓度空间中缩放 PSD，并获得 PSD 的固有形状。因此，通过结合 N0* 、Dm 和代表归一化 PSD 形状的修改伽玛函数，我们能够以小于 20% 的绝对平均相对误差来近似关键云变量（例如 IWC）以及可远程观测的云属性（例如 Z）。基本思想是能够使用两个独立的测量来检索 PSD。我们还提出了从归一化 PSD 导出的冰云关键参数的参数化。我们还研究了冰晶质量尺寸关系中存在的不确定性对参数化和归一化 PSD 方法的影响。
The ice particle size distribution (PSD) is fundamental to the quantitative description of a cloud. It is also crucial in the development of remote sensing retrieval techniques using radar and/or lidar measurements. The PSD allows one to link characteristics of individual particles (area, mass, and scattering properties) to characteristics of an ensemble of particles in a sampling volume (e.g., visible extinction (σ), ice water content (IWC), and radar reflectivity (Z)). The aim of this study is to describe a normalization technique to represent the PSD. We update an earlier study by including recent in situ measurements covering a large variety of ice clouds spanning temperatures ranging between −80°C and 0°C. This new data set also includes direct measurements of IWC. We demonstrate that it is possible to scale the PSD in size space by the volume‐weighted diameter Dm and in the concentration space by the intercept parameter N0∗ and obtain the intrinsic shape of the PSD. Therefore, by combining N0∗ , Dm, and a modified gamma function representing the normalized PSD shape, we are able to approximate key cloud variables (such as IWC) as well as cloud properties which can be remotely observed (such as Z) with an absolute mean relative error smaller than 20%. The underlying idea is to be able to retrieve the PSD using two independent measurements. We also propose parameterizations for ice cloud key parameters derived from the normalized PSD. We also investigate the effects of uncertainty present in the ice crystal mass‐size relationships on the parameterizations and the normalized PSD approach.