THE WEATHER THE WEATHER RESEARCH AND RESEARCH AND

FORECAST MODELFORECAST MODEL(WRF)(WRF)

What makes WRF next-generation What makes WRF next-generation mesoscale forecast model ?mesoscale forecast model ?

Advance the understanding and the prediction of mesoscale precipitation systems and to promote closer ties between the research and operational forecasting communities.

Efficiency, portability, maintainability, and extensibility.

SOFTWARE SOFTWARE ARCHITECTUREARCHITECTURE

Runge-Kutta MethodRunge-Kutta Method

Driver LayerDriver Layer

Handles run-time allocation and parallel decomposition of model domain data structures.

Organization, management, interaction, and control over nested domains, including the main time loop in the model.

High level interfaces to I/O operations on model domains.

It is interface to other components when WRF is part of a larger coupled system of applications.

Mediation LayerMediation Layer

Encompasses one time-step of a particular dynamical core on a single model domain.

The current WRF implementation uses the Message Passing Interface (MPI) communication package.

Shared-memory parallelism over tiles in the solve routines is using OpenMP.

ICC’s High Performance ComputingICC’s High Performance Computing

Model LayerModel Layer

Comprises the actual computational routines that make up the model: advection, diffusion, physical parameterizations, and so forth.The subroutines are called through a standard Model Layer Interface. The interface ensures that a Model Layer package incorporated into WRF will work on any parallel computer.Model layer routines have data dependencies rely on the mediation layer to perform the necessary interprocessor communication.

The RegistryThe Registry

It is a concise database of information about WRF data structures and a mechanism for automatically generating large sections of WRF code.The Registry data base is a collection of tables that lists and describes the WRF state variables and arrays with their attributes such as dimensionality and so fourth.Registry generates code for interfaces between layers of the infrastructure, packing and unpacking code for communication and nesting, and field-by-field calls to routines for model I/O.

Moving NestsMoving Nests

PERFORMANCEPERFORMANCE

Implementation of Wildland Implementation of Wildland Fire Model Component in Fire Model Component in

the WRF modelthe WRF model

Functionalities of the Wildland Fire Model Functionalities of the Wildland Fire Model ComponentComponent

Extension of the Clark-Hall atmospheric model.Atmosphere-wildland fire simulation model has been developed to represent a complex interactions between fires and local winds.Helps to track atmospheric wind velocities and calculate fire spread more precisely.Handles large releases of buoyancy and accurately represent fine-scale motions in complex terrain.Ingest large-scale gridded data to incorporate a changing mesoscale atmospheric environment.Telescope down to the meter-sized fine dynamic scales of vortices in the fire line through horizontal and vertical grid refinement.

BenefitsBenefits

The availability of a coupled atmosphere-fire model in a well-supported community model for eventual community research.Can build a stable framework in other scientific components related to the Wildland Fire Research and Development Collaboratory.Provide eventual operational capability with operational applications like smoke management …A test of WRF with strong forcing at small scales.Reduction in the redundancy of effort developing needed capabilities within the Clark-Hall model .

Numerical modelNumerical model

• Background- 3-D nonhydrostatic atmospheric prediction model coupled with

an empirical fire spread model with sensible and latent heat flux from the fire feed back to the atmosphere to produce fire winds.

- The atmospheric winds drive the fire propagation.

• Wildfire simulation model represents the complex interactions between a fire and local wind.

BURNUP algorithmBURNUP algorithm

Characterizes how the fire consumes fuels of different sizes over time.

Equation :

1-F = exp(-t/W)

Implementation of Fire Module in WRFImplementation of Fire Module in WRF

Fire module will be implemented as an added physics option in WRF.Fire-atmosphere coupling will occur through passing winds from the lowest WRF level to the fire module.The fire module will use those winds to predict the fire spread and subsequent heat and water vapor emissions.Heat and water vapor emissions from the fire will be passed back to WRF and distributed vertically through an assumed extinction depth.

Initialization of Fire EnvironmentInitialization of Fire Environment

Three environmental factors that influence fire behavior are :

1. Topography

2. Weather

3. Fuel

TopographyTopography

Fires spread much faster in upslope than flat ground.

Fine-scale topography features as a factor in local airflows plays a role in fire behavior.

WeatherWeather

Weather impacting the fire.The weather impacts on the fire can be obtained by the winds model in WRF.Winds model could be used to simulate changes in dead fuel moisture which responds with time lags corresponding to the size of the fuel particles.

- A second feedback loop between the fire and the environment.

FuelFuel

Not all vegetation is burnable.

Live vegetation may be dried and ignited by fire (live fuel).

Forest floor needles, cured grasses and branches (dead fuel) play more important role in fire behavior.

Links with other modulesLinks with other modules

WRF-Chem is an atmospheric chemistry package linked to WRF for simulation of atmospheric chemistry and aerosols.

The combined application of WRF-Chem and WRF-Fire will allow the user to create a simulation of Wildland fire.

Numerical Simulation of WildfiresNumerical Simulation of Wildfires

ReferencesReferences

URLs

http://mathworld.wolfram.com/Runge-KuttaMethod.html http://www.wrf-model.org/index.php http://www.llnl.gov/computing/hpc/training/#training_materials http://box.mmm.ucar.edu/research/wildfire/wrf/wrf_summary.html http://box.mmm.ucar.edu/research/wildfire/wrf/wrf_fire.html

Research Papers

The Weather Research and Forecast Model: Software Architecture and Performanceby J Michalakes, J.Dudhia, D.Gill, T.Henderson, J.Klemp, W.Skamarock, W.Wang

Implementation of Wildland Fire Model Component in the Weather Research and Forecasting (WRF) modelby Janice Coen (MMM/RAP) and Ned Patton (MMM)

WRF-Fire: A Coupled Atmosphere-Fire Module for WRFby Ediward G.Patton and Janice L.Coen.National Center for Atmospheric Research, Boulder, CO