Parametrizations of Liquid and Ice Clouds’ Optical Properties in Operational Numerical Weather Prediction Models

Parametrization of radiation transfer through clouds is an important factor in the ability of Numerical Weather Prediction models to correctly describe the weather evolution. Here we present a practical parameterization of both liquid droplets and ice optical properties in the longwave and shortwave...

Full description

Saved in:
Bibliographic Details
Published in:Atmosphere 2021-01, Vol.12 (1), p.89
Main Authors: Muskatel, Harel. B., Blahak, Ulrich, Khain, Pavel, Levi, Yoav, Fu, Qiang
Format: Article
Language:English
Subjects:
Aerosols
Albedo
Aspect ratio
Asymmetry
Attenuation
Clouds
Extinction coefficient
Graupel
Hydrometeors
Ice
Ice clouds
ice particles
Light attenuation
Long wave radiation
Numerical weather forecasting
NWP
Optical properties
Optics
Parameterization
Particle size
Prediction models
Radiation
Radiation-cloud interactions
radiative transfer
Short wave radiation
Spectra
water droplets
Weather
Weather forecasting
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Parametrization of radiation transfer through clouds is an important factor in the ability of Numerical Weather Prediction models to correctly describe the weather evolution. Here we present a practical parameterization of both liquid droplets and ice optical properties in the longwave and shortwave radiation. An advanced spectral averaging method is used to calculate the extinction coefficient, single scattering albedo, forward scattered fraction and asymmetry factor (βext, ϖ, f, g), taking into account the nonlinear effects of light attenuation in the spectral averaging. An ensemble of particle size distributions was used for the ice optical properties calculations, which enables the effective size range to be extended up to 570 μm and thus be applicable for larger hydrometeor categories such as snow, graupel, and rain. The new parameterization was applied both in the COSMO limited-area model and in ICON global model and was evaluated by using the COSMO model to simulate stratiform ice and water clouds. Numerical weather prediction models usually determine the asymmetry factor as a function of effective size. For the first time in an operational numerical weather prediction (NWP) model, the asymmetry factor is parametrized as a function of aspect ratio. The method is generalized and is available on-line to be readily applied to any optical properties dataset and spectral intervals of a wide range of radiation transfer models and applications.
ISSN:2073-4433
2073-4433
DOI:10.3390/atmos12010089