9.4    Feature Calibration Alignment for the WRF model

Nehrkorn, Thomas, Atmospheric and Environmental Research Inc., and Thomas AulignŽ, NCAR

Numerical Weather Prediction models have dramatically improve in recent years, but they still often exhibit significant phase errors. These errors are particularly difficult to correct in data assimilation because they are usually not normally distributed. However, they can have a major impact of the forecast of important meteorological features such as cloud systems and hurricanes. We will present a package to compute alignment fields based on observations and WRF model background. Two-dimensional alignment is computed through a non-linear minimization process, with a series of constraints applied on the alignment to insure a physical result. A particular focus is devoted to the conservation of the internal balance in the model fields. Results for a hurricane case and cloud-resolving simulations will be shown, with a significant impact on the forecast skill.