View source for How to diagnose fuel properties in WRF-SFIRE

{{users guide}}
The fuel properties in [[WRF-SFIRE]] are given in file [https://github.com/openwfm/WRF-SFIRE/blob/master/test/em_fire/namelist.fire namelist.fire].  These serve to create coefficients in the Rothermel's formula. To aid diagnostics it is useful to graph the resulting fire spread rate as a function of wind and slope. The graphs are available in metric units, as well as in English units for direct comparison with the published spread rate graphs for the Scott-Burgan fuel categories.

==Prerequisites==

* [[How to run WRF-Fire|Compile and run WRF-Fire]]
* [[Matlab]]

==Location of the codes==
* The fuel properties of every category of the fuel are defined in file [https://github.com/openwfm/WRF-SFIRE/blob/master/test/em_fire/namelist.fire '''namelist.fire'''], which needs to be in the current directory.
* The fire rate of spread computation is done in file '''[https://github.com/openwfm/WRF-SFIRE/blob/master/phys/module_fr_sfire_phys.F module_fr_sfire_phys.F]''', split between two subroutines. First, the coefficients at every point are precomputed from fuel properties in subroutine '''set_fire_params''' at initialization. In every time step, the spread rate at a point is then computed from those coefficients in subroutine '''fire_ros'''.
* The computation has been duplicated in Matlab for diagnostic purposes in file  '''[https://github.com/openwfm/wrf-fire-matlab/blob/master/vis3d/fire_ros.m fire_ros.m]'''
* The plot routine to create graphs like shown here is '''[https://github.com/openwfm/wrf-fire-matlab/blob/master/vis3d/plot_fuel.m plot_fuel.m]'''

==Heat flux diagnostics==
* '''plot_fuel''' also computes and prints several diagnostic quantities derived from fuel properties, including total heat density generated by the combustion of the fuel over time (J/m<sup>2</sup>), and the maximal heat flux density (W/m<sup>2</sup>) from the initial slope of the fuel loss curve. These can be compared with the statistic printed by WRF-Fire while running (maximal heat flux density, total heat flux of the fire, total heat generated by the fire).

==Step-by-step instructions==
===Acquire and visualize ROS===
* Run WRF-SFIRE, you can kill it right after the the first time step, or follow the instructions for '''fire_ros.exe''' in '''standalone'''
* There will be file '''fuels.m''' created in the current directory.
* '''git clone https://github.com/openwfm/wrf-fire-matlab''' and copy the file '''fuels.m''' to the directory created.
* '''cd''' in MATLAB to the directory and type '''startup'''
* '''cd''' in MATLAB to the directory with the file '''fuels.m''' and type '''fuels'''. 
* This will create variable '''fuel'''. Say you want to check fuel 3. Type '''fuel(3)''' to see what is there.
* Type '''plot_fuel(fuel(3))''' to create the graph below in metric units, and '''plot_fuel(fuel(3),'sb')''' for the same units as in Scott and Burgan (2005). Type '''help plot_fuel''' for further information. Note: The graph data were created in WRF-SFIRE and stored in the '''fuel''' variable.

===Compare with Rothermel method===
* '''edit fire_ros''' to see the Rothermel fire rate of spread calculation recreated in Matlab.
* Type '''big(check_ros(fuel))''' to make sure the calculation in Matlab is the same as in WRF-SFIRE, which will compare the calculation with ROS on a number of data points stored in file '''fuels.m'''. It should return rounding error only (less than 1e-4) 
* '''Note - at the moment, the checks in plot_fuel are fine, but check_ros is not. '''Opened issue https://github.com/openwfm/wrf-fire-matlab/issues/5 and upstream in WRF-SFIRE.'''

==Diagnostics provided==

The '''plot_fuel''' command displays the graph of rate of spread as a function of wind speed, slope, and fuel moisture.

[[Image:Grass-metric.png|400px]][[Image:Grass-english.png|400px]]
[[Image:Grass-slope.png|400px]][[Image:Grass-fmc.png|400px]]

==Works with==
''To be updated''
*  Version {{WRF-Fire-commit|334bf9417b5397ed3692b8f469a4914ed433e051|16 Sep 2010}}
*  Version  {{WRF-Fire-commit|bce8561325b4ced49303e941931d78f63b3c843b|29 Aug 2012}} and hopefully later
* Matlab R2010a, 2012a, and hopefully later

==References==

* Anderson, H. E., 1982. ''Aids to determining fuel models for estimating fire behavior.'' U.S. Forest Service General Technical Report INT-122. Ogden, UT. [http://www.fs.fed.us/rm/pubs_int/int_gtr122.pdf pdf] (The original 13 fuel models)
* Baughman, R. G. and F. A. Albini.,1980. ''Estimating midflame windspeeds.'' In Sixth Conference on Fire and Forest Meteorology, Seattle, WA (Society of American Foresters) [http://firemodels.fire.org/downloads/behaveplus/publications/Baughman_and_Albini_1980_6thConFireForMet_EstMidflamWind.pdf pdf]  (Windspeed reduction from 20ft)
* Rothermel, R.C., 1972. ''A mathematical model for predicting fire spread in wildland fuels.'' Res. Pap. INT-115. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station. 40 pp. [[Media:Rothermel-1972-MMP.pdf|pdf]] (The original for reference)
* Rothermel, R. C., 1983. ''How to predict the spread and intensity of forest and range fires.'' U.S. Forest Service General Technical Report INT-143. Ogden, UT. [http://firemodels.fire.org/downloads/behaveplus/publications/Rothermel_INT-143_1983.pdf pdf] (Updated version)
* Scott, J. H. and Burgan, R. E., 2005. ''Standard fire behavior fuel models: a comprehensive set for use with Rothermel's surface fire spread model.'' Gen. Tech. Rep. RMRS-GTR-153. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, 72 pp. [http://www.fs.fed.us/rm/pubs/rmrs_gtr153.html  pdf] (More detailed fuel models, with rate of spread curves)

==External links==
* [http://www.firemodels.org/index.php/behaveplus-introduction/behaveplus-publications BehavePlus publications] at [http://fire.org fire.org] 
* [[Wikipedia:Log wind profile]]
* [http://www.meted.ucar.edu/fire/s591/models/ Fire model matrix] in [http://www.meted.ucar.edu/dl_courses/fire/ Advanced Fire Weather Forecasters Course (S-591)] at [http://www.meted.ucar.edu meted.ucar.edu]
* [http://math.fire.org Firefighter Math: Self-Paced Math Course]: [http://math.fire.org/index.php?option=com_content&task=view&id=71&Itemid=85 Fuels for Fire Behavior] at [http://fire.org fire.org]
* [http://www.forestencyclopedia.net/p/p140 Fuels, Weather, and Fire Behavior] at [http://www.forestencyclopedia.net forestencyclopedia.net]

[[Category:WRF-Fire]]
[[Category:Howtos|Diagnose fuel properties in WRF-Fire]]