Abstract

A method for the joint determination of microphysical aerosol characteristics, namely, the complex refractive index \(m = m_{\text{real}}^{{}} + im_{\text{image}}^{{}}\) and spherical-particle size distribution function U(r), from the data of nighttime lidar sensing at wavelengths of 355–1064 nm is proposed. During their simultaneous estimations, it is useful to directly minimize the discrepancy functional Φ(m) in the range of the physically justified m. The principal limitations due to a wider region of the global minima of Φ(m) appear at \(m_{{{\text{image}}}}^{{{\text{true}}}} \in \) [0.01, 0.04] and give rise to a potential shift of the resulting values of \(m_{\text{real}}^{\text{est}}\) and \(m_{\text{image}}^{\text{est}}\). A simultaneous use of several functionals gives a better estimate of m due to different sets of the respective optical characteristics. The problem in retrieving the size distribution function is caused by the information content of the coarse particle measurements. The statistical regularization method offers an unambiguous estimation of U(r) for the mean radius up to 3 µm and gives an admissible estimate for larger radii. The algorithms are tested on eight values of absorption, when one value corresponding to one \(m_{\text{image}}^{\text{true}}\) is associated with 50 empirical models of the distribution function.

中文翻译：

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从激光雷达测量同时重建复数折射率和粒度分布函数：测试开发的算法

摘要

联合确定微物理气溶胶特性的方法，即复折射率\（m = m _ {\ text {real}} ^ {{}} + im _ {\ text {image}} ^ {{}} \）从夜间激光雷达在355-1064 nm波长处的数据，提出了球形颗粒尺寸分布函数U（r）。在他们同时进行估算的过程中，在物理上合理的m范围内直接最小化差异函数Φ（m）很有用。由于Φ（m）的全局最小值的更宽范围而导致的主要限制出现在\（m _ {{{\ text {image}}}} ^ {{{{\ text {true}}}} \ in \）[0.01，0.04]并引起\（m _ {\ text {real}} ^ {\ text {est}} \）和\（m _ {\ text {image}} ^ { \ text {est}} \）。由于各个光学特性的不同集合，几种功能的同时使用可以更好地估计m。检索尺寸分布函数的问题是由粗颗粒测量的信息内容引起的。统计正则化方法可对最大3 µm的平均半径提供U（r）的明确估计，并为较大半径提供可接受的估计。当一个值对应一个\（m _ {\ text {image}} ^ {\ text {true}} \）时，对八个吸收率值测试算法 与分布函数的50个经验模型相关联。