Weather Research & Forecasting Model (WRF) Stacey Pensgen ESC 452 – Spring ’06

WRF Outline What is it? Timeline The Technical Aspect Future Work Conclusion

What is it? Project to develop a “next generation” mesoscale forecast model that will enhance the understanding and prediction of mesoscale systems. Collaborative effort between – NCAR (National Center for Atmospheric Research) – NCEP (National Centers for Environmental Prediction) – FSL (Forecast Systems Laboratory) – NOAA (National Oceanic & Atmospheric Administration) – AFWA (Air Force Weather Agency) – Other institutions & organizations

What is it? Promote closer ties and a common framework between the research and operational forecasting communities. Will also be used in research and operational applications. Besides forecasting work, WRF is also intended for regional climate predictions, air quality simulations, and idealized dynamical studies.

What is it? Goal is to (based on it’s evaluations) eventually replace existing models, such as the Mesoscale Model (MM5) at NCAR, ETA at NCEP, and RUC at FSL. Targeted for a 1-10 km grid scale. Improved physics, especially for treatment & diagnosing convection and mesoscale precipitation.

Timeline 1 st release (WRF 1.0) was November 30, 2000 Full implementation as a research model by the end of Full implementation as an operational forecasting model at NCEP and AFWA by the end of 2004 Operational performance refinement from

WRF compared to ETA, MM5, and actual observations.

Technical Aspect WRF is intended to be compatible – physics packages can be easily exchanged with other models. WRF 1.0 prototype uses geometric height as vertical coordinate, but prototype also available that uses hydrostatic pressure as vertical coordinate. Programming language: Fortran90!

Technical Aspect Included physics package plug-ins: – Microphysics – Boundary Layer – Surface Layer – Ground Layer – Subgrid 3D Turbulence/Diffusion – Cumulus Parameterization – Radiation (shortwave & longwave)

Future Plans Working to add other more advanced physical parameters: – Land surface processes – Baroclinic waves – Squall lines – Supercell thunderstorms

Future Plans Development work on 3DVAR system - a joint effort by all working on WRF to improve initialization using multiple observation techniques, including satellite (in addition to traditional synoptic forms).

Conclusion WRF Model is important because: – Provides a more advanced forecasting model for mesoscale precipitation events. – Promotes closer ties between research & forecasting fields. – Easily compatible with a variety of computing architectures. – Intended for a wide range of applications.

References unix.mcs.anl.gov/~michalak/ecmwf98/final.html unix.mcs.anl.gov/~michalak/ecmwf98/final.html o2001pp_wcs.pdf o2001pp_wcs.pdf