A single cloud in a blue sky

High resolution model development

Kilometre and sub-kilometre scale versions of the Met Office Unified Model are a key component of the Met Office's forecast system, providing vital information about small-scale weather phenomena such as severe storms which may lead to flooding. To improve our forecasts we need to understand how processes in the atmosphere operate on these scales.

The details of convection and convective initiation, for example, often depend on small scale features. These fall into two categories - those associated with the surface topography (hills, coastlines etc) and those originating from larger scale structures in the atmosphere (fronts etc). The representation of both of these are improved if the model resolution is increased through having more detailed surface data and through having a higher resolution representation of the atmosphere itself. We are similarly interested in improving model representation of other weather elements such as wind, fog, clouds and surface temperatures.

The accuracy of forecasts can depend on the way we represent small-scale processes like convection and turbulence in the model. In order to understand and improve model representation of these small scale features we are working to improve key parts of the model, in particular the convective, boundary layer, turbulence and microphysics parametrizations. In order to understand the effects of changing these parts of the model we carry out case study work i.e. rerunning particular cases of interest with a view to understanding the model performance.

Improvements to our high-resolution models also leads to improvements in our high-resolution ensemble forecasts, and we continue to work closely with the Ensemble Forecasting teams to understand predictability at the convective scale.

Key aims

  • Investigate and improve convection, boundary layer and mixing parametrizations with a view to improving the representation of convection in the Met Office Numerical Weather Prediction models model.

  • Work on higher resolution models (500 m grid length) with a view improving our understanding of the models at 1.5 km grid length and also for possible future operational implementation.

  • Investigate the representation of convection in the model in more extreme situations than usually found in the UK (e.g. supercells on the US Great Plains).

  • Investigate the potential benefits of coupling high resolution atmospheric models to ocean, wave and hydrology models.

  • Model other non-convective mesoscale phenomena at high resolution (e.g. drainage flows in valleys, fog etc.)