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Evaluation of Higher-order Quadrature Schemes in Improving Computational Efficiency for Orientation-averaged Single-Scattering Properties of Nonspherical Ice Particles
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  • Ines FENNI,
  • Kwo-Sen Kuo,
  • Mark Haynes,
  • Ziad S Haddad,
  • Hélène Roussel

Corresponding Author:ines.fenni@gmail.com

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Kwo-Sen Kuo
National Aeronautics and Space Administration (NASA), National Aeronautics and Space Administration (NASA)
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Mark Haynes
Jet Propulsion Laboratory, Jet Propulsion Laboratory
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Ziad S Haddad
Jet Propulsion Lab (NASA), Jet Propulsion Lab (NASA)
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Hélène Roussel
Sorbonne University, Sorbonne University
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We evaluate several high-order quadrature schemes for accuracy and efficacy in obtaining orientation-averaged single-scattering properties (SSPs). We use the recently developed, highly efficient MIDAS to perform electromagnetic scattering calculations to compare and evaluate the gain in efficiency from these quadrature schemes. MIDAS is shown to be superior to DDSCAT, a popular discrete dipole approximation (DDA) method. This study is motivated by the fact that quality physical precipitation retrievals rely on using accurate orientation-averaged SSPs derived from realistic hydrometeors as input to radiative transfer simulations. The DDA has been a popular choice for single-scattering calculations, due to its versatility with respect to target geometry. However, being iterative-solver-based (ISB), the most used DDA codes, e.g. DDSCAT and ADDA, must solve the scattering problem for each orientation of the target separately. As the size parameter and geometric anisotropy of the hydrometeor increase, the number of orientations needed to obtain accurate orientation-averages can increase drastically and so does the computation cost incurred by the ISB-DDA methods. MIDAS is a Direct-Solver-Based (DSB) code, using Method of Moments (MoM) instead of DDA, its decomposition of the original large matrix with a high rank into multiple more manageable smaller matrices of lower ranks makes it much more computationally efficient and stable while maintaining excellent accuracy. In addition, direct solvers consider all requested orientations at once, giving MIDAS further advantage over popular ISB-DDA methods. Combined with high-order quadrature for orientation average, MIDAS can be orders of magnitude more efficient in obtaining RTM-ready SSPs than existing ISB-DDA methods.
16 Jun 2021Published in Journal of Geophysical Research: Atmospheres volume 126 issue 11. 10.1029/2020JD034172