WRF:
Weather Research and Forecasting Model
WRF: Weather Research and Forecasting Model
– Used for
both research and operational forecasting
WRF: Weather Research and Forecasting Model
– 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
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 has two dynamical cores:
The Advanced Research WRF (ARW) and
Nonhydrostatic MesoscaleModel (NMM)
WRF has two dynamical cores: The Advanced Research WRF (ARW) and Nonhydrostatic MesoscaleModel (NMM)
– Dynamical core includes mostly
- advection,
- pressure gradients,
- Coriolis,
- buoyancy,
- filters,
- diffusion, and
- timestepping
The Advanced Research WRF (ARW) and Nonhydrostatic MesoscaleModel (NMM)
both are
Eulerianmass 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)
The Advanced Research WRF (ARW) and Nonhydrostatic MesoscaleModel (NMM)
Both are downloadable in
the same WRF tar file
The Advanced Research WRF (ARW) and Nonhydrostatic MesoscaleModel (NMM)
what are the things shared between the dynamical cores
- Physics,
- the software framework, and
- parts of data pre- and post-processing
ARW and NMM can be used for
- Atmospheric physics/parameterization research
- Case-study research
- Real-time NWP and forecast system research
- Data assimilation research
- Teaching dynamics and NWP
ARW only can be used for
- 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)
WRF Modeling System Flow chart
Modeling System Components
WRF Pre-processing System
WRF Model (ARW and NMM dynamical cores)
Graphics and verification tools including MET
explain:
WRF Pre-processing System
- Real-data interpolation for NWP runs (WPS)
- Program for adding more observations to analysis (obsgrid)
explain:
WRF Model (ARW and NMM dynamical cores)
- Initialization programs for real and (for ARW) idealized data (real.exe/ideal.exe)
- – Numerical integration program (wrf.exe)
WPS and WRF Program Flow
Real-Data Applications of WRF
- Numerical weather prediction
- Meteorological case studies
- Regional climate
- Applications: air quality, wind energy, hydrology, etc
Real-Data Applications need
time-independent information for chosen domain(simulation grid area)
Real-Data Applications
GEOGRID program
- Map projection information
- Topographic information
Real-Data Applications
GEOGRID program
Map projection information
- 2d gridded latitude,
- longitude,
- Coriolis parameter,
- map-scale factors, etc
Real-Data Applications
GEOGRID program
Topographic information
2d gridded elevation,
vegetation and soil categories, etc.
Real-Data Applications need the following
- Need time-dependent information
- Initial conditions (initial analysis time)
- Boundary conditions (later times)
- except if running WRF globally
- UNGRIB and METGRIDprograms
- except if running WRF globally
Real-Data Applications
UNGRIBand METGRIDprograms
- 3d fields of horizontal wind, temperature, geopotential height, relative humidity
- 2d fields of surface or sea-level pressure, surface temperature, relative humidity, horizontal winds
- Time-sensitive land-surface fields: snow-cover, soil temperature, soil moisture
Real-Data Applications
Regional domains need
specified lateral boundary conditions at later times (e.g. every 6 hours) through forecast period
- 3d fields of horizontal wind, temperature, geopotential height, water vapor
- 2d field of surface pressure
Long simulations (> 1 week) also need
lower boundary condition at later times
- 2d fields of sea-surface temperature, sea-ice, vegetation fraction
Lateral Boundary Conditions (linear in time)
– The wrfbdyfile contains
later gridded information at model points in a zone (e.g.) 5 points wide around the domain
Lateral Boundary Conditions (linear in time)
– The wrfbdyfile contains later gridded information at model points in a zone (e.g.) 5 points wide around the domain
– The boundary fields are
linearly time-interpolated from boundary times to the current model time
Lateral Boundary Conditions (linear in time)
– The wrfbdyfile contains later gridded information at model points in a zone (e.g.) 5 points wide
around the domain
– The boundary fields are linearly time-interpolated from boundary times to the current model time
– This specifies
the outer values, and is used to nudge the next 4 interior points
