The main objective of the Action is to provide clear theoretical guidance on convection parameterizations for climate and numerical weather prediction models. Both global and regional atmospheric models are concerned. The Action achieves this objective by creating a core theoretical group to address the fundamental issues of convection parameterization. Modellers and theoreticians join together under this framework. The Action proposes a clear pathway for more coherent and effective parameterizations by integrating existing operational schemes and new theoretical ideas. Proposed alternative approaches intend to replace conventional tuning-based approaches. The Action complements extensive inter-comparison based validations performed by operational modellers.
The Action responds particularly to urgent needs which have arisen from increasing the resolutions of forecast models. In these new-generation models, not only the traditional approximations break down, but associated physical processes become increasingly complex. Thus, the parameterization must be extensively re-formulated with more sophisticated physics under new constraints. The Action contributes to reduce uncertainties in weather forecasts and climate projection by overcoming the often weak physical basis of the current parameterizations. Particular benefits will be in prediction of highly unusual extreme weather events, such as local heavy precipitation, tropical cyclone trajectories etc. The IPCC will be a particular international agent that will benefit from the present Action.
