DOI: 10.1002/jgrd.50167
论文题名: Applicability of the Rayleigh-Gans approximation for scattering by snowflakes at microwave frequencies in vertical incidence
作者: Tyynelä J. ; Leinonen J. ; Westbrook C.D. ; Moisseev D. ; Nousiainen T.
刊名: Journal of Geophysical Research Atmospheres
ISSN: 21698996
出版年: 2013
卷: 118, 期: 4 起始页码: 1826
结束页码: 1839
语种: 英语
英文关键词: microwave
; Rayleigh-Gans approximation
; scattering
; snowflakes
Scopus关键词: Backscattering
; Microwaves
; Monomers
; Scattering
; Solar radiation
; Asymmetry parameter
; Correction factors
; Discrete dipole approximation
; Electromagnetic spectra
; Rayleigh-Gans approximation
; Sample correlation coefficients
; Single-scattering albedo
; snowflakes
; Snow
; accuracy assessment
; albedo
; atmospheric correction
; backscatter
; correlation
; electromagnetic radiation
; extinction
; frequency analysis
; microwave radiation
; parameterization
; Rayleigh number
; scattering
; snow
英文摘要: The applicability of the Rayleigh-Gans approximation (RGA) for scattering by snowflakes is studied in the microwave region of the electromagnetic spectrum. Both the shapes of the single ice crystals, or monomers, and their amounts in the modeled snowflakes are varied. For reference, the discrete-dipole approximation (DDA) is used to produce numerically accurate solutions to the single-scattering properties, such as the backscattering and extinction cross-sections, single-scattering albedo, and the asymmetry parameter. We find that the single-scattering albedo is the most accurate with only about 10% relative bias at maximum. The asymmetry parameter has about 0.12 absolute bias at maximum. The backscattering and extinction cross-sections show about - 65% relative biases at maximum, corresponding to about - 4.6 dB difference. Overall, the RGA agrees well with the DDA computations for all the cases studied and is more accurate for the integrated quantities, such as the single-scattering albedo and the asymmetry parameter than the cross-sections for the same snowflakes. The accuracy of the RGA seems to improve, when the number of monomers is increased in an aggregate, and decrease, when the frequency increases. It is also more accurate for less dense monomer shapes, such as stellar dendrites. The DDA and RGA results are well correlated; the sample correlation coefficients of those are close to unity throughout the study. Therefore, the accuracy of the RGA could be improved by applying appropriate correction factors. Key PointsRayleigh-Gans approximation is applicable for snowflakes at microwavesThe biases are well correlated and can be improved by correction factorsSSA and asymmetry parameter are more accurate than cross sections © 2013. American Geophysical Union. All Rights Reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/63900
Appears in Collections: 影响、适应和脆弱性 气候减缓与适应
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作者单位: Department of Physics, University of Helsinki, PO Box 48, FI-00014, Helsinki, Finland; Finnish Meteorological Institute, Helsinki, Finland; Department of Applied Physics, Aalto University, Espoo, Finland; Department of Meteorology, University of Reading, Berkshire, United Kingdom
Recommended Citation:
Tyynelä J.,Leinonen J.,Westbrook C.D.,et al. Applicability of the Rayleigh-Gans approximation for scattering by snowflakes at microwave frequencies in vertical incidence[J]. Journal of Geophysical Research Atmospheres,2013-01-01,118(4)