WRF & ARW

What is WRF?

WRF is the short form of Weather Research and Forecasting Model, i.e., a numerical weather prediction system. WRF is a state-of-the-art atmospheric modeling system designed for both meteorological research and numerical weather prediction. It offers a host of options for atmospheric processes and can run on a variety of computing platforms.

• Used for both research and operational forecasting
• It is a supported "community model", i.e. a free and shared resource with distributed development and centralized support
• Its development is led by NCAR, NOAA/ESRL and NOAA/NCEP/EMC with partnerships at AFWA, FAA, DOE/PNNL and collaborations with universities and other government agencies in the US and overseas

WRF Community Model

• Version 1.0 WRF was released December 2000
• Version 2.0: May 2004 (add nesting)
• Version 3.0: April 2008 (add global ARW version)
• ...  (major releases in April, minor releases in summer)
• Version 3.8: April 2016
• Version 3.8.1: August 2016
• Version 3.9: April 2017 
• Version 3.9.1(.1) (August 2017)

What is ARW?

WRF has two dynamical cores: The Advanced Research WRF (ARW) and Non-hydrostatic Mesoscale Model (NMM)

Dynamical core includes mostly advection, pressure-gradients, Coriolis, buoyancy, filters, diffusion, and time-stepping

Both are Eulerian mass dynamical cores with terrain-following vertical coordinates

ARW support and development are centered at NCAR/MMM

NMM development is centered at NCEP/EMC and support is provided by NCAR/DTC (operationally now only used for HWRF)

Usage of WRF

ARW and NMM

• Atmospheric physics/parameterization research
• Case-study research
• Real-time NWP and forecast system research
• Data assimilation research
• Teaching dynamics and NWP

ARW only

• Regional climate and seasonal time-scale research
• Coupled-chemistry applications
• Global simulations
• Idealized simulations at many scales (e.g. convection, baroclinic waves, large eddy simulations)

Examples of WRF Forecast

1. Hurricane Katrina (August, 2005): Moving 4 km nest in a 12 km outer domain
2. US Convective System (June, 2005): Single 4 km central US domain

Real-Data Applications

• Numerical weather prediction
• Meteorological case studies
• Regional climate
• Applications: air quality, wind energy, hydrology, etc.

Ref: https://www.climatescience.org.au/sites/default/files/WRF_Overview_Dudhia_3.9.pdf
Ref: http://www2.mmm.ucar.edu/wrf/users/