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Volume 14, issue 24
Atmos. Chem. Phys., 14, 13719-13737, 2014
https://doi.org/10.5194/acp-14-13719-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
Atmos. Chem. Phys., 14, 13719-13737, 2014
https://doi.org/10.5194/acp-14-13719-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 22 Dec 2014

Research article | 22 Dec 2014

A two-habit model for the microphysical and optical properties of ice clouds

C. Liu1, P. Yang1, P. Minnis2, N. Loeb2, S. Kato2, A. Heymsfield3, and C. Schmitt3 C. Liu et al.
  • 1Department of Atmospheric Sciences, Texas A&M University, College Station, Texas, USA
  • 2Science Directorate, NASA Langley Research Center, Hampton, Virginia, USA
  • 3National Center for Atmospheric Research, Boulder, Colorado, USA

Abstract. To provide a better representation of natural ice clouds, a novel ice cloud model is developed by assuming an ice cloud to consist of an ensemble of hexagonal columns and 20-element aggregates with specific habit fractions at each particle size bin. The microphysical and optical properties of this two-habit model (THM) are compared with both laboratory and in situ measurements, and its performance in downstream satellite remote sensing applications is assessed. The ice water contents and median mass diameters calculated based on the THM closely agree with in situ measurements made during 11 field campaigns. In this study, the scattering, absorption, and polarization properties of ice crystals are calculated with a combination of the invariant imbedding T matrix, pseudo-spectral time domain, and improved geometric-optics methods over an entire practical range of particle sizes. The phase functions, calculated based on the THM, show close agreement with counterparts from laboratory and in situ measurements and from satellite-based retrievals. When the THM is applied to the retrievals of cloud microphysical and optical properties from MODIS (the Moderate Resolution Imaging Spectroradiometer) observations, excellent spectral consistency is achieved; specifically, the retrieved cloud optical thicknesses based on the visible/near infrared bands and the thermal infrared bands agree quite well. Furthermore, a comparison between the polarized reflectivities observed by the PARASOL satellite and from theoretical simulations illustrates that the THM can be used to represent ice cloud polarization properties.

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An ice cloud model is developed by assuming an ice cloud to be an ensemble of columns and aggregates with specific habit fractions at each particle size bin. The microphysical and optical properties of this two-habit model (THM) are compared with both laboratory and in situ measurements. When the THM is applied to ice cloud property retrieval, excellent spectral consistency is achieved. A comparison between observed and theoretical polarized reflectivities illustrates the applicability of THM.
An ice cloud model is developed by assuming an ice cloud to be an ensemble of columns and...
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