Universität zu Köln

Ori, Davide ORCID: 0000-0002-9964-2200 and Kneifel, Stefan ORCID: 0000-0003-2220-2968 (2018). Assessing the uncertainties of the discrete dipole approximation in case of melting ice particles. J. Quant. Spectrosc. Radiat. Transf., 217. S. 396 - 407. OXFORD: PERGAMON-ELSEVIER SCIENCE LTD. ISSN 1879-1352

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Abstract

We studied the applicability of the Discrete Dipole Approximation (DDA) for scattering by partially melted snowflakes in the microwave region. The DDA accuracy in the case of a liquid water coated ice sphere was tested at various particle sizes, water layer thicknesses, frequencies and DDA grid resolutions. We found that the backscattering and absorption cross section show the largest biases with respect to the Mie reference. The highest discrepancies were found for the thinnest water coating and the lowest frequency. We applied a previously published method to separately analyze the errors due to the representation of particle shape and discretization. The accuracy of the DDA seems to decrease particularly when only a single dipole is used to represent some structural element of the target with large refractive index. A similar behavior was also found by testing the variation of the scattering properties of complex shaped melting snowflakes at different grid resolutions. From both experiments we conclude that single isolated water dipoles should be avoided when modeling the scattering properties of melting snowflakes in the microwave using DDA. Although we found that a stability criterion which is commonly used for pure ice particles is not sufficient for melting particles, the DDA results in general converge to the exact Mie solution when shape and discretization errors are reduced by using a refined grid. (C) 2018 Elsevier Ltd. All rights reserved.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Ori, Davide UNSPECIFIED orcid.org/0000-0002-9964-2200 UNSPECIFIED Kneifel, Stefan UNSPECIFIED orcid.org/0000-0003-2220-2968 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-173742
DOI:	10.1016/j.jqsrt.2018.06.017
Journal or Publication Title:	J. Quant. Spectrosc. Radiat. Transf.
Volume:	217
Page Range:	S. 396 - 407
Date:	2018
Publisher:	PERGAMON-ELSEVIER SCIENCE LTD
Place of Publication:	OXFORD
ISSN:	1879-1352
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Geosciences > Institute for Geophysics and Meteorology
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language SCATTERING PROPERTIES; LIGHT-SCATTERING; PART II; MICROWAVE; RADAR; LAYER; MODEL; HYDROMETEORS; SIMULATIONS; ATTENUATION Multiple languages Optics; Spectroscopy Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/17374