Aurora 1.5 extends Microsoft’s Earth-system foundation model by expanding its variable coverage from four to twenty-six atmospheric fields, spanning surface, pressure-level, wind, temperature, humidity, precipitation, and radiation data. The updated model introduces hourly temporal resolution and probabilistic ensemble forecasting, developed through multi-stage fine-tuning that applies controlled perturbations within the model’s latent conditioning pathway. In benchmark evaluations, Aurora 1.5’s probabilistic forecasts outperformed the ECMWF dynamical ensemble on the large majority of evaluated targets and reduced tropical cyclone track error by roughly a third compared with the original Aurora model.
