Evaluating Prognostic Parameterizations Using ARM Data at the Three Major ARM Sites
Iacobellis, S.F. and Somerville, R.C.J., Scripps Institution of Oceanography, University of California, San Diego
Fourteenth Atmospheric Radiation Measurement (ARM) Science Team Meeting
To test recently developed prognostic parameterizations based on detailed cloud microphysics, we have compared single-column model (SCM) output with ARM observations at the SGP, NSA and TWP sites. We focus on comparing predicted cloud amounts and radiative quantities strongly dependent on clouds, such as downwelling surface shortwave radiation. Our results generally demonstrate the superiority of parameterizations based on comprehensive treatments of cloud microphysics and cloud-radiative interactions. At the SGP and NSA sites, the SCM results simulate the ARM measurements well and are often more realistic than parameterizations found in conventional operational forecasting models. However, at the TWP site, the SCM produces less realistic results, judged against ARM data, and is not consistently superior to the operational parameterizations. In an effort to understand and eliminate these model deficiencies at the TWP site, we have carried out numerical experiments, varying spin-up and start times and other aspects of the SCM. The results show how unrealistic aspects of the model low cloud simulations are related to errors in the SCM temperature and humidity fields. They also suggest ways to develop improved parameterizations better suited to simulating cloud-radiation interactions at the TWP site and thus perhaps in the tropics generally.
Note: This is the poster abstract presented at the meeting; an extended version was not provided by the author(s).
