DOI: 10.1002/2014JD021616
论文题名: Scattering properties of modeled complex snowflakes and mixed-phase particles at microwave and millimeter frequencies
作者: Ori D. ; Maestri T. ; Rizzi R. ; Cimini D. ; Montopoli M. ; Marzano F.S.
刊名: Journal of Geophysical Research: Atmospheres
ISSN: 2169897X
出版年: 2014
卷: 119, 期: 16 起始页码: 9931
结束页码: 9947
语种: 英语
Scopus关键词: algorithm
; frequency analysis
; in situ measurement
; Mie theory
; optical property
; radar
; radiative forcing
; scattering
; snow cover
; water content
英文摘要: A microphysically based algorithm (named Snow Aggregation and Melting (SAM)) that models snowflakes composed of a collection of hexagonal columns by simulating a random aggregation process is presented. SAM combines together pristine columns with multiple dimensions to derive complex aggregates constrained to size-mass relationship obtained by data collected from in situ measurements. The model also simulates the melting processes occurring for environmental temperatures above 0°C and thus define the mixed-phase particles structure. The single-scattering properties of the modeled snowflakes (dry and mixed phased) are computed by using a discrete dipole approximation (DDA) algorithm which allows to model irregularly shaped targets. In case of mixed-phased particles,realistic radiative properties are obtained by assuming snow aggregates with a 10% of melted fraction. The single-scattering properties are compared with those calculated through Mie theory together with Maxwell-Garnett effective medium approximation using both a homogeneous sphere and a layered-sphere models. The results show that for large-size parameters there are significant differences between the radiative properties calculated using complex microphysical and optical algorithms (i.e.,SAM and DDA) and those obtained from simplified assumptions as the layered-sphere models (even when the radial ice density distribution of the aggregated snowflakes is perfectly matched). Finally,some applications to quantitative precipitation estimation using radar data are presented to show how the resulting differences in the basic optical properties would propagate into radar measurable. Large discrepancies in the derivation of the equivalent water content and snowfall rate from radar measurements could be observed when large-size parameters are accounted for. © 2014. 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/63049
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 Biological,Geological and Environmental Sciences, University of Bologna, Bologna, Italy; Department of Physics and Astronomy, University of Bologna, Bologna, Italy; Institute of Methodologies for the Environmental Analysis, National Research Council of Italy, Potenza, Italy; Center of Excellence CETEMPS, University of L’Aquila, L’Aquila, Italy; Department of Information Engineering, University of Rome La Sapienza, Rome, Italy
Recommended Citation:
Ori D.,Maestri T.,Rizzi R.,et al. Scattering properties of modeled complex snowflakes and mixed-phase particles at microwave and millimeter frequencies[J]. Journal of Geophysical Research: Atmospheres,2014-01-01,119(16)