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Are AI Models Capturing Atmosphere Dynamics?

12.810 Final Proj

Ken Yan

Cover photo generated by ChatGPT

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NWP vs AI Weather Forecast

FourCastNet: Fourier ForeCasting Neural Network

Spherical Fourier Neural Operator

FourCastNet (NVIDIA) Pangu (Huawei)

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Literature Review

“Yes!” Papers

  • Medina et al. (2025):
    • Sensitivity Analysis of cyclone Xthynia
    • SNFO (FourCastNet-v2)
  • Hakim & Masanam (2024):
    • Reponses to Perturbations
    • Pangu

“Not there yet” Papers

  • Sun et al. (2024):
    • Gradient Wind Balance
    • FourCastNet
  • Charlton-Perez et al. (2024):
    • Peak wind in storm Ciarán
    • FourCastNet, Pangu-Weather, GraphCast and FourCastNet-v2
  • Bonavita (2024):
    • Sub-Synoptic and mesoscale phenomena
    • Pangu-Weather, FourCastNet and GraphCast
  • ECMWF (2023):
    • Overly smooth forecasts
    • increasing bias with forecast lead time
    • Poor performance in predicting tropical cyclone intensity

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Data and Methods

AI models and Gradient Wind Balance

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AI Model Outputs Availability

  • Pangu-Weather and other MLWP models like FourCastNet and GraphCast have been run in a semi-operational configuration at ECMWF since August 2023 and their outputs both graphical and numerical are freely available from the ECMWF archives

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Gradient Wind Balance (Sun et al., 2024)

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Choose TC from 2018-2024 (testing set)

  • Hurricane Lee in 2023 … became a Category 1 storm on Wednesday, September 6. By the evening of September 7, it had developed into a Category 5 storm.

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  • Init time at weak phase: Sep 5 0000 UTC

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Weak Phase init, model = pangu

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Choose TC from 2018-2024 (testing set)

  • Hurricane Lee in 2023 … became a Category 1 storm on Wednesday, September 6. By the evening of September 7, it had developed into a Category 5 storm.
  • Init time at strong phase: Sep 7 1200 UTC

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Strong Phase init, model = fourcastnetv2

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Compared Quantity: Extracted Wind vs Gradient Wind

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Hurricane Lee, init = 2023/09/05 (Weak Phase), lead = 144 hour

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Hurricane Lee, init = 2023/09/05 (Weak Phase), lead = 144 hour

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6 cat5 hurricanes considered!

Beryl (2024 June)

Dorian (2019 Aug)

Lorenzo (2019 Sep)

Ian (2022 Sep)

Lee (2023 Sep)

Milton (2024 Oct)

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Weak Phase init

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Strong Phase init

“…The lack of the expected balance, i.e., the difference between the full wind and the gradient wind, is most noticeable in forecasts initiated during the strong phase of the TCs.” (Sun et al., 2024)

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Supp Slides

Typhoon Bebinca (upper right)

Dessert Bebinca (lower right)

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