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Title: Short-term Time Step Convergence in a Climate Model

A testing procedure is designed to assess the convergence property of a global climate model with respect to time step size, based on evaluation of the root-mean-square temperature difference at the end of very short (1 h) simulations with time step sizes ranging from 1 s to 1800 s. A set of validation tests conducted without sub-grid scale parameterizations confirmed that the method was able to correctly assess the convergence rate of the dynamical core under various configurations. The testing procedure was then applied to the full model, and revealed a slow convergence of order 0.4 in contrast to the expected first-order convergence. Sensitivity experiments showed without ambiguity that the time stepping errors in the model were dominated by those from the stratiform cloud parameterizations, in particular the cloud microphysics. This provides a clear guidance for future work on the design of more accurate numerical methods for time stepping and process coupling in the model.
 [1] ;  [1] ;  [2] ;  [3]
  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  3. Univ. of Michigan, Ann Arbor, MI (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 1942-2466
Grant/Contract Number:
AC05-76RL01830; AC04-94AL85000; SC0006684; AC05-00OR22725
Published Article
Journal Name:
Journal of Advances in Modeling Earth Systems
Additional Journal Information:
Journal Volume: 7; Journal Issue: 1; Journal ID: ISSN 1942-2466
American Geophysical Union (AGU)
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
54 ENVIRONMENTAL SCIENCES; convergence; climate model; short-term; time step size