Evaluation of the Forecasts of the Energetics in the BRAMS, ETA and WRF Regional Models: Part I - Winter

Abstract

The aim of this study is to evaluate the terms of the eddy kinetic energy (K’) equation in the 24 h and 48 h forecasts of the regional models BRAMS, WRF and ETA. These models were operationally integrated at the Weather Forecast and Climate Studies Center (CPTEC). The evaluation period was from June 1 to August 31, 2016 and the domain was the region of South America. The horizontal resolution of the three models is 5 km and the temporal is 6 h. The initial and boundary conditions were obtained from the Global Forecast System (GFS) of the National Centers for Environmental Prediction (NCEP), with a horizontal resolution of 0.25°. The models were initialized only with the analysis of 1200 UTC. The non-hydrostatic version of the three models was run, with WRF using Kain-Frisch cumulus parameterization, ETA Betts-Miller culumus parameterization and BRAMS Grell and Freitas. In general, the three models underestimate K‘ in mid-latitudes, mainly over the oceans, however, ETA is the one that underestimates the least and WRF the most. Regarding the terms of baroclinic and barotropic conversion, in addition to the term of ageostrophic flow convergence, the three models have a similar pattern of these three terms with that of GFS numerical analysis.

Keywords
kinetic energy; evaluation; regional models