Christopher A. Davis, National Center for Atmospheric Research (NCAR)
Abstract for weekly colloquium on Thursday, October 20, 2016 at 4 pm in PAS 220
MPAS is a non-hydrostatic global model that employs a numerical solver similar to what is used in the WRF model, but integrated on a centroidal Veronoi mesh. The mesh, consisting mainly of hexagonal elements, allows smooth refinements in centroid spacing (horizontal resolution). The variable-resolution configuration of MPAS allows smooth transitions in resolution that minimize unphysical behavior in transition regions. We present a synthesis of real-time forecasts of eastern Pacific tropical cyclones in 2014 conducted using both uniform and variable-resolution configurations of MPAS to demonstrate the effectiveness of the variable-resolution approach. The centroid spacing is either quasi-uniform 15 km or variable from 60 to 15 km, with the highest resolution centered over the eastern North Pacific. Forecasts out to day 7-8 are very similar in the two configurations. Biases in tropical cyclone formation at long lead times are traced to errors in physical parameterizations. We also present some results from the 2015 eastern North Pacific and 2016 western North Pacific tropical cyclone seasons to show how the physical parameterizations have improved, and along with it so has the overall model performance.