Observational diagnosis of cloud phase in the winter Antarctic atmosphere for parameterizations in climate models

Yong Sang Choi, Chang Hoi Ho, Sang Woo Kim, Richard S. Lindzen

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21 Scopus citations


The cloud phase composition of cold clouds in the Antarctic atmosphere is explored using data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instruments for the period 2000-2006. We used the averaged fraction of liquid-phase clouds out of the total cloud amount at the cloud tops since the value is comparable in the two measurements. MODIS data for the winter months (June, July, and August) reveal liquid cloud fraction out of the total cloud amount significantly decreases with decreasing cloud-top temperature below 0°C. In addition, the CALIOP vertical profiles show that below the ice clouds, low-lying liquid clouds are distributed over ∼20% of the area. With increasing latitude, the liquid cloud fraction decreases as a function of the local temperature. The MODIS-observed relation between the cloud-top liquid fraction and cloud-top temperature is then applied to evaluate the cloud phase parameterization in climate models, in which condensed cloud water is repartitioned between liquid water and ice on the basis of the grid point temperature. It is found that models assuming overly high cut-offs (≫ -40°C) for the separation of ice clouds from mixed-phase clouds may significantly underestimate the liquid cloud fraction in the winter Antarctic atmosphere. Correction of the bias in the liquid cloud fraction would serve to reduce the large uncertainty in cloud radiative effects.

Original languageEnglish
Pages (from-to)1233-1245
Number of pages13
JournalAdvances in Atmospheric Sciences
Issue number6
StatePublished - Nov 2010

Bibliographical note

Funding Information:
Acknowledgements. This work was funded by Korean Center for Atmospheric Sciences and Earthquake Research 2010–1178, and US Department of Energy grant DE-FG02-01ER63257. The MODIS and CALIOP data were obtained from LAADS (Level 1 and Atmosphere Archive and Distribution System) at the NASA Goddard Space Flight Center and ASDC (Atmospheric Sciences Data Center) at the NASA Langley Research Center, respectively.


  • Cloud parameterization
  • Cloud phase
  • Cloud radiative effect
  • Mixed-phase clouds
  • Polar cloud


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