Journal of Climate

Article: pp. 2302–2324 | Full Text | PDF (3.91M)

The Community Land Model and Its Climate Statistics as a Component of the Community Climate System Model

Robert E. Dickinson

Georgia Institute of Technology, Atlanta, Georgia

Keith W. Oleson, Gordon Bonan, Peter Thornton, and Mariana Vertenstein

National Center for Atmospheric Research, Boulder, Colorado

Forrest Hoffman

Oak Ridge National Laboratory, Oak Ridge, Tennessee

Zong-Liang Yang

University of Texas at Austin, Austin, Texas

Xubin Zeng

The University of Arizona, Tucson, Arizona

(Manuscript received 23 January 2005, in final form 10 August 2005)

DOI: 10.1175/JCLI3742.1

ABSTRACT

Several multidecadal simulations have been carried out with the new version of the Community Climate System Model (CCSM). This paper reports an analysis of the land component of these simulations. Global annual averages over land appear to be within the uncertainty of observational datasets, but the seasonal cycle over land of temperature and precipitation appears to be too weak. These departures from observations appear to be primarily a consequence of deficiencies in the simulation of the atmospheric model rather than of the land processes. High latitudes of northern winter are biased sufficiently warm to have a significant impact on the simulated value of global land temperature. The precipitation is approximately doubled from what it should be at some locations, and the snowpack and spring runoff are also excessive. The winter precipitation over Tibet is larger than observed. About two-thirds of this precipitation is sublimated during the winter, but what remains still produces a snowpack that is very large compared to that observed with correspondingly excessive spring runoff. A large cold anomaly over the Sahara Desert and Sahel also appears to be a consequence of a large anomaly in downward longwave radiation; low column water vapor appears to be most responsible. The modeled precipitation over the Amazon basin is low compared to that observed, the soil becomes too dry, and the temperature is too warm during the dry season.

 

 

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