Autumn 2017 | The terrain-following sigma coordinate has been implemented in many Numerical Weather Prediction (NWP) systems, including the Weather Research and Forecasting (WRF) model, and has been used with success for many years. However, terrain-following coordinates are known to induce small-scale horizontal and vertical accelerations over areas of steep terrain due to the reflection of topography in the model levels. These accelerations introduce error into the model equations and can impact model forecasts, especially as… Read More