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Radar signatures of snowflake riming: A modeling study.

Authors
  • Leinonen, Jussi1
  • Szyrmer, Wanda2
  • 1 Jet Propulsion Laboratory California Institute of Technology Pasadena California USA.
  • 2 Department of Atmospheric and Oceanic Sciences McGill University Montreal Quebec Canada. , (Canada)
Type
Published Article
Journal
Earth and space science (Hoboken, N.J.)
Publication Date
Aug 01, 2015
Volume
2
Issue
8
Pages
346–358
Identifiers
PMID: 27981073
Source
Medline
Keywords
Language
English
License
Unknown

Abstract

The capability to detect the state of snowflake riming reliably from remote measurements would greatly expand the understanding of its global role in cloud-precipitation processes. To investigate the ability of multifrequency radars to detect riming, a three-dimensional model of snowflake growth was used to generate simulated aggregate and crystal snowflakes with various degrees of riming. Three different growth scenarios, representing different temporal relationships between aggregation and riming, were formulated. The discrete dipole approximation was then used to compute the radar backscattering properties of the snowflakes at frequencies of 9.7, 13.6, 35.6, and 94 GHz. In two of the three growth scenarios, the rimed snowflakes exhibit large differences between the backscattering cross sections of the detailed three-dimensional models and the equivalent homogeneous spheroidal models, similarly to earlier results for unrimed snowflakes. When three frequencies are used simultaneously, riming appears to be detectable in a robust manner across all three scenarios. In spite of the differences in backscattering cross sections, the triple-frequency signatures of heavily rimed particles resemble those of the homogeneous spheroids, thus explaining earlier observational results that were compatible with such spheroids.

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