MOGREPS ensemble-based Clear Air Turbulence products

The Met Office Global and Regional Prediction Scheme (MOGREPS) ensemble forecasting system became formally operational in September, 2008, having already run for several years in trials. It runs twice daily with 24 members at a resolution of 24 km over the North Atlantic and Europe (MOGREPS-R). A global model (MOGREPS-G) runs twice daily at a resolution of 90 km, primarily to provide lateral boundary conditions to the regional model. General meteorological products from both the regional and global models can be used by our forecasters in their assessment of the most likely outcomes and risks of high impact weather.

A trial using MOGREPS-R data to generate a probabilistic clear air turbulence forecast was carried out for a three month trial period in 2009 using the Ellrod TI1 turbulence indicator. We present the results from the trial using objective verification against automated aircraft observations from the Global Aircraft Data Set (GADS) and compare the probabilistic forecasts with the current World Area Forecast Centre (WAFC) gridded CAT forecasts derived from the UK and US deterministic models.