Leveraging data-driven weather models for improving numerical weather prediction skill through large-scale spectral nudging
<|reference_start|>Leveraging data-driven weather models for improving numerical weather prediction skill through large-scale spectral nudging: Operational meteorological forecasting has long relied on physics-based numerical weather prediction (NWP) models. Recently, this landscape is facing disruption by the advent of data-driven artificial intelligence (AI)-based weather models, which offer tremendous computational performance and competitive forecasting skill. However, data-driven models for medium-range forecasting generally suffer from major limitations, including low effective resolution and a narrow range of predicted variables. This study illustrates the relative strengths and weaknesses of these competing paradigms using the GEM (Global Environmental Multiscale) and GraphCast models to represent physics-based and AI-based approaches, respectively. By analyzing global predictions from these two models against observations and analyses in both physical and spectral spaces, this study demonstrates that GraphCast-predicted large scales outperform GEM, particularly for longer lead times. Building on this insight, a hybrid NWP-AI system is proposed, wherein GEM-predicted large-scale state variables are spectrally nudged toward GraphCast predictions, while allowing GEM to freely generate fine-scale details critical for weather extremes. Results indicate that this hybrid approach is capable of leveraging the strengths of GraphCast to enhance the prediction skill of the GEM model. Importantly, trajectories of tropical cyclones are predicted with enhanced accuracy without significant changes in intensity. Furthermore, this new hybrid system ensures that meteorologists have access to a complete set of forecast variables, including those relevant for high-impact weather events.<|reference_end|>
@article{husain2024leveraging,
    title={Leveraging data-driven weather models for improving numerical weather
  prediction skill through large-scale spectral nudging},
    author={Syed Zahid Husain, Leo Separovic, Jean-Franc{c}ois Caron, Rabah
  Aider, Mark Buehner, St'ephane Chamberland, Ervig Lapalme, Ron
  McTaggart-Cowan, Christopher Subich, Paul A. Vaillancourt, Jing Yang, Ayrton
  Zadra},
    journal={arXiv preprint arXiv:2407.06100},
    year={2024},
    archivePrefix={arXiv},
    eprint={2407.06100},
    primaryClass={physics.ao-ph cs.LG}
}