Analyzing Low Frequency Atmospheric Variability in GFS Models: Performance and Differences

Jan 09, 2026

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This study examines the performance of GFS models in simulating low frequency atmospheric variability (LFV). It compares two versions of the GFS models (GFS1 and GFS2), focusing on their differences in LFV and their dynamical interpretations. Using monthly data from 1949 to 2002 for both models and NCEP reanalysis, the analysis reveals that both models can produce realistic LFV patterns. However, discrepancies are attributed to biases in tropical heating and the eastward extension of the Pacific jet.

1 low frequency variability 2 gfs models 3 tropical heating 4 atmospheric simulation 5 climate modelling 6 gfs1 vs gfs2 7 monthly data analysis 8 pacific jet extension

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Analyzing Low Frequency Atmospheric Variability in GFS Models: Performance and Differences

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Low Frequency Atmospheric Variability in GFS Models Peitao Peng Acknowledgment: Bhaskar, Arun and Huug
Purposes • The performance of GFS models in simulating the low frequency variability (LFV) of the atmosphere; • Differences between the two versions of GFS models in LFV; • Dynamical interpretation of the differences.
Data Model: Monthly Z200 and Prate from the AMIP-type runs (1949-2002) with GFS1 and GFS2. (Note: the difference between GFS1 and GFS2 is that they uses different radiation packages) OBS: Monthly Z200 from NCEP reanalysis (1949-2002)

Mechanism: “bias” in tropical heating Pacific jet eastward extension LFV eastward shifting
Summary • Either version of the GFS models can generate very realistic LFV patterns. • Some differences in LFV patterns between the two models can be explained the “bias” in tropical heating.