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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 107, NO. D13, 4181, doi:10.1029/2001JD000742, 2002

Parameterization of shortwave ice cloud optical properties for various particle habits

Jeffrey R. Key

Office of Research and Applications, National Environmental Satellite, Data, and Information Service, National Oceanic and Atmospheric Administration, Madision, Wisconsin, USA


Ping Yang

Department of Atmospheric Sciences, Texas A&M University, College Station, Texas, USA


Bryan A. Baum

NASA Langley Research Center, Hampton, Virginia, USA


Shaima L. Nasiri

Cooperative Institute for Meteorological Satellite Studies, University of Wisconsin, Madison, Wisconsin, USA


Abstract

The relative importance of ice clouds in the climate system is highly uncertain. Measurements of their microphysical properties are sparse, especially given their complex structure and large variability in particle size, shape, and density. To better understand the role of ice clouds in the climate system, parameterizations of their radiative properties are needed. The shortwave bulk optical properties of seven ice particle shapes, or “habits,” are parameterized as a function of the effective “radius” and ice water content by integrating the scattering properties over 30 in situ size distributions. The particle habits are solid and hollow hexagonal columns, hexagonal plates, two- and three-dimensional bullet rosettes, aggregates of columns, and dendrites. Parameterizations of the volume extinction coefficient, single-scattering albedo, and the asymmetry parameter are presented for 6, 24, and 56 band shortwave schemes from 0.2 to 5.0 μm. Applications to downwelling flux and upwelling radiance calculations indicate that differences in fluxes for various habits can be more than 15%, and differences in retrievals of cloud optical depth from satellite visible reflectances can be more than 50%.

Published 12 July 2002.

Index Terms: 3359 Meteorology and Atmospheric Dynamics: Radiative processes; 0360 Atmospheric Composition and Structure: Transmission and scattering of radiation; 3360 Meteorology and Atmospheric Dynamics: Remote sensing.

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Citation: Key, J. R., P. Yang, B. A. Baum, and S. L. Nasiri (2002), Parameterization of shortwave ice cloud optical properties for various particle habits, J. Geophys. Res., 107(D13), 4181, doi:10.1029/2001JD000742.