Incremental Update Initialization Procedure for Navy Operational Mesoscale Model - NORAPS

摘要

Since radiosonde observations are required to be reported on mandatory constantpressure levels, observational data analysis for numerical weather prediction is usually conducted on these constant pressure levels. On the other hand, model forecasts are usually calculated on sigma levels to avoid lower boundary problems due to complex terrains. Vertical interpolation between the pressure and sigma levels therefore, needed to generate initial conditions for the forecast model and to produce first guesses for the analysis. The interpolation errors in initial conditions can be reduced if only analysis increments (analyzed corrections to first guess fields) are interpolated to the sigma levels. Furthermore, mesoscale forecast models generally include very high vertical resolutions at low levels to calculate vertical fluxes in planetary boundary layer. The vertical resolution of forecast model is generally much higher than the resolution of analysis at how levels. By adding the interpolated analysis increments to high resolution first guesses, the detailed vertical profiles at low levels can be preserved in initial conditions.