Real-Time Prediction of the Tropics using the Model for Prediction Across Scales (MPAS)

The recently developed Model for Prediction Across Scales (MPAS) was used to produce global forecasts in real time during August and September of 2013. MPAS is a non-hydrostatic model, integrated on a horizontally-unstructured Voronoi mesh using a C-grid discretization appropriate for mesoscale flows. The unstructured mesh allows for a gradual transition between relatively coarse resolution over most of the globe, to higher resolution in a region of interest. In this talk, we will examine the overall performance of, and the relative differences between, two sets of forecasts. One set is comprised of 10-day forecasts on a quasi-uniform 15-km grid. The other set is composed of 10 day forecasts on a variable mesh that ranges from 60-km grid spacing over most of the globe to 15 km over the tropical Atlantic. Results indicate that the two forecasts retain high correlations for a longer time over the Atlantic than over other tropical regions. There are fairly rapid departures between the forecasts in mid-latitudes relative to the tropics. These differences are quantified, as are overall forecast errors and the errors in tropical cyclone position and intensity in the major tropical cyclone basins.