Diagnosing problems with the models is the first step towards solving problems and improving our forecasts.
Continual monitoring of the models performance, in conjunction with detailed comparisons against a wide range of satellite and in-situ observations and feedback from forecasters enables us to develop physically based and testable hypothesis of the causes of model problems and systematic biases, and develop model changes which address them. This process involves specialists both within the Met Office from the Atmospheric Processes groups and Global Modelling, and external collaborators around the world. We also work with the Seamless Prediction group to examine the performance of the model across the full range of temporal and spatial scales forecast by the Unified Model.
The proposed model changes are then tested by running a forecast trial, where an operational forecast model is re-run for a period, modified by the inclusion of one or more proposed changes. The impact of the changes can then be evaluated by looking in detail at the Verification results and any other suitable observations. As the issue is investigated further a package of complementary changes is built which is then tested, prior to operational use, in a Parallel Suite run alongside the operational versions of the Unified Model This acts as a final quality control on the changes and to ensure that the forecasters and down-stream systems are prepared for the changes.