Quantitative characterization of spurious numerical oscillations in 48 CMIP5 models

Kerrie L. Geil, Xubin Zeng

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Spurious numerical oscillations (SNOs) (e.g., Gibbs oscillations) can appear as unrealistic spatial waves near discontinuities or sharp gradients in global model fields (e.g., orography) and have been a known problem in global models for decades. Multiple methods of oscillation reduction exist; consequently, the oscillations are presumed small in modern climate models and hence are rarely addressed in recent literature. Here we use two metrics to quantify SNOs in 13 variables from 48 Coupled Model Intercomparison Project Phase 5 models along a Pacific ocean transect near the Andes. Results show that 48% of nonspectral models and 95% of spectral models have at least one variable with SNO amplitude as large as, or greater than, atmospheric interannual variability. The impact of SNOs on climate simulations should be thoroughly evaluated and further efforts to substantially reduce SNOs in climate models are urgently needed.

Original languageEnglish (US)
Pages (from-to)5066-5073
Number of pages8
JournalGeophysical Research Letters
Issue number12
StatePublished - Jun 28 2015


  • global climate models
  • model evaluation
  • numerical approximation
  • uncertainty quantification

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)


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