Which of the following descriptions best represent the overarching design of your forecasting model?
- Machine learning-based weather prediction.
What techniques did you use to initialise your model? (For example: data sources and processing of initial conditions)
The model is initialized with ERA5 at 0.25° resolution, with the 12 latest samples available at the time of submission (with a 6-hour sampling between each of the 12 samples). For each initial sample, an autoregressive prediction is performed for 150 steps to cover the entire period. The lead time of each prediction is 6 hours.
If any, what data does your model rely on for real-time forecasting purposes?
Our model is not designed specifically for real-time forecasting.
What types of datasets were used for model training? (For example: observational datasets, reanalysis data, NWP outputs or satellite data)
The model was trained with only ERA5 data at 0.25° resolution, from 1979 to 2019.
Please provide an overview of your final ML/AI model architecture (For example: key design features, specific algorithms or frameworks used, and any pre- or post-processing steps)
Our ESFM model builds on the Aurora architecture, with an encoder-processor-decoder structure. The key modification to the Aurora architecture that is employed in the WeatherQuest challenge is the addition of multiple decoder heads for each variable to output probabilistic predictions. We use the pretrained checkpoint from the Aurora model and further train our model with 8 decoder heads for 18k steps on 32 GPUs. The training loss is a combination of latitude-weighted MAE and CRPS.
Have you published or presented any work related to this forecasting model? If yes, could you share references or links?
A preprint will be released soon.
Before submitting your forecasts to the AI Weather Quest, did you validate your model against observational or independent datasets? If so, how?
Our forecasts are not externally validated. We directly submit the output of the autoregressive predictions.
Did you face any challenges during model development, and how did you address them?
The main challenges are technical and computational difficulties related to the size of the model (1.3B parameters). The training is remarkably stable in terms of convergence of the loss function but is impacted by various errors (e.g., NCCL errors, CPU out-of-memory errors).
Are there any limitations to your current model that you aim to address in future iterations?
The main limitation of our model is that it has been trained with only 1-step ahead prediction, no rollout loss function was employed. This implies that there is no optimization over multiple autoregressive predictions. In the next competition phase, our model will feature rollout loss training.
A second limitation was observed during the WeatherQuest challenge and is related to the dispersion of the ensemble members predicted by the decoder heads. We observed that our 8 decoder heads are overdispersive, leading to a few members that are below the 20% quintile or above the 80% quintile. We are addressing this limitation in our ongoing developments.
Are there any other AI/ML model components or innovations that you wish to highlight?
Other innovations brought by ESFM are related to data loading, variable encoding, and pretraining strategies but they were not used in the AI Weather Quest challenge.
Who contributed to the development of this model? Please list all individuals who contributed to this model, along with their specific roles (e.g., data preparation, model architecture, model validation, etc) to acknowledge individual contributions.
Dr. Fanny Lehmann, data preparation, model training, model validation, forecasts submission
Piotr Wilczyński, model training, model validation, forecasts submission
Dr. Firat Ozdemir, model architecture, model training
Dr. Yun Cheng, model architecture, data loading
Dr. Salman Mohebi, model architecture, data loading