GCM Cloud Diagnostics

Norris and Weaver (2001) evaluated synoptic cloudiness in the NCAR Community Climate Model version 3 by comparing observed and simulated cloud properties averaged as a function of meteorological process (i.e., compositing). This provides a more physically-based evaluation than averaging over time and better reveals the presence of compensating errors. The study of Norris and Weaver compared cloud properties as a function of large-scale midtropospheric vertical motion over the midlatitude North Pacific during July.

Cloud properties compared were:

  • cloud radiative forcing [Fig. 1a] [Fig. 1b] [Fig. 1c]
  • all-sky liquid water path [Fig. 2]
  • frequency distributions of cloud optical thickness and cloud top pressure categories
    [Fig. 3a] [Fig. 3b] [Fig. 3c]

    Also see the presentations

  • Variability of Extratropical Cloudiness in the Community Climate System Model Version 2
  • Evaluation of Synoptic Cloudiness in the Community Climate System Model

    Download observational composite data used by Norris and Weaver to evaluate your own GCM

    Let me know if you find these data useful: jnorris@ucsd.edu