LaDCast is a new global latent-diffusion framework introduced for medium-range ensemble weather forecasting.
It generates hourly ensemble forecasts in a learned latent space by compressing high-dimensional ERA5 reanalysis fields into a compact representation using an autoencoder.
A transformer-based diffusion model is employed to produce sequential latent updates with arbitrary hour initialization.
LaDCast incorporates Geometric Rotary Position Embedding (GeoRoPE) to consider the Earth's spherical geometry, a dual-stream attention mechanism for efficient conditioning, and sinusoidal temporal embeddings for capturing seasonal patterns.
The model achieves deterministic and probabilistic forecasting skill comparable to the European Centre for Medium-Range Forecast IFS-ENS, without explicit perturbations.
LaDCast excels in tracking rare extreme events like cyclones, providing more accurate trajectory predictions compared to established models.
By operating in latent space, LaDCast significantly reduces storage and computational requirements, offering a practical approach to real-time kilometer-scale resolution forecasting.
The code and models for LaDCast are open-source, and training and evaluation pipelines are available at https://github.com/tonyzyl/ladcast.