Evaluation of WindNinja Simulations in Canyon Topography

This study describes a validation of the surface wind model WindNinja conducted over different types of complex terrain. The Weather Research and Forecasting model (WRF) 2 km output was used as input for our WindNinja simulations. We tested the surface wind model for two case sites in California characterized by canyons of different terrain complexity. Simulations were conducted with different initialization methods and numerical solvers within WindNinja. The first simulations were conducted by initializing the model from a singular point. Further simulations were initialized using a spatial method with explicit input values over the whole modeling domain. The simulation results were then compared to WRF model output to see if WindNinja could improve upon the mesoscale model’s forecast in a canyon setting. Statistical error metrics were calculated to compare the model output to the observations and thus validate the performance of both WindNinja and WRF at several stations for the two case sites. WindNinja performed only marginally better than WRF over simpler terrain. WRF performed best in complex terrain with steep canyons compared to WindNinja, which struggled with increased wind speeds at peaks and ridges.