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An Improved Beta Method for Ice Cloud Property Retrievals: Theory
Author(s) -
Saito Masanori,
Yang Ping,
Heidinger Andrew K.,
Li Yue
Publication year - 2020
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2019jd031863
Subject(s) - cloud computing , cirrus , ice cloud , radiative transfer , effective radius , remote sensing , environmental science , beta (programming language) , infrared , property (philosophy) , computer science , meteorology , computational physics , physics , geology , optics , astrophysics , philosophy , epistemology , galaxy , operating system , programming language
The beta method has long been used for ice cloud property retrievals with the utilization of thermal infrared observations. The method assumes an idealized cloud that is isothermal and does not scatter radiation, which results in systematic biases in ice cloud property retrievals. We improve the beta method by taking into account, for the first time since the beta method was developed, a nonisothermal cloud layer and the cloud scattering effects. The improved beta method provides almost unbiased cloud optical thickness retrievals for typical cirrus clouds and reduces the systematic biases of effective particle radius retrievals for optically thin clouds. The improved beta method does not involve either Jacobian or iterative radiative transfer calculations. As a result, this method is computationally efficient, robustly applicable to any historical and current spaceborne thermal infrared observations, and capable of processing a large amount of satellite data.