Data driven weather forecasts trained and initialised directly from observations

TL;DR

This paper introduces a novel neural network approach that predicts future weather directly from raw observational data without relying on reanalyses or physics-based models, promising more flexible and observation-centric weather forecasting.

Contribution

The authors propose a new method for training neural networks solely on observational data, avoiding dependence on data assimilation and reanalyses, enabling more direct and potentially more accurate weather predictions.

Findings

Preliminary results show successful 12-hour ahead forecasts of weather observations.

The approach captures physical process evolutions directly from observations.

It offers a flexible framework for joint Earth system forecasting.

Abstract

Skilful Machine Learned weather forecasts have challenged our approach to numerical weather prediction, demonstrating competitive performance compared to traditional physics-based approaches. Data-driven systems have been trained to forecast future weather by learning from long historical records of past weather such as the ECMWF ERA5. These datasets have been made freely available to the wider research community, including the commercial sector, which has been a major factor in the rapid rise of ML forecast systems and the levels of accuracy they have achieved. However, historical reanalyses used for training and real-time analyses used for initial conditions are produced by data assimilation, an optimal blending of observations with a physics-based forecast model. As such, many ML forecast systems have an implicit and unquantified dependence on the physics-based models they seek to challenge. Here we propose a new approach, training a neural network to predict future weather purely from historical observations with no dependence on reanalyses. We use raw observations to initialise a model of the atmosphere (in observation space) learned directly from the observations themselves. Forecasts of crucial weather parameters (such as surface temperature and wind) are obtained by predicting weather parameter observations (e.g. SYNOP surface data) at future times and arbitrary locations. We present preliminary results on forecasting observations 12-hours into the future. These already demonstrate successful learning of time evolutions of the physical processes captured in real observations. We argue that this new approach, by staying purely in observation space, avoids many of the challenges of traditional data assimilation, can exploit a wider range of observations and is readily expanded to simultaneous forecasting of the full Earth system (atmosphere, land, ocean and composition).