Difference between revisions of "SFIRE variables"
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{| border="1" | {| border="1" | ||
|+ Fire variables on fire grid | |+ Fire variables on fire grid | ||
| − | + | | scope="col" | Variable name | |
| − | + | | scope="col" | Description | |
| − | + | | scope="col" | Unit | |
|- | |- | ||
| − | + | | scope="row" | NFUEL_CAT | |
|fuel data | |fuel data | ||
| | | | ||
|- | |- | ||
| − | + | | scope="row" | ZSF | |
|height of surface above sea level | |height of surface above sea level | ||
|m | |m | ||
|- | |- | ||
| − | + | | scope="row" | DZDXF | |
|surface gradient x | |surface gradient x | ||
|1 | |1 | ||
|- | |- | ||
| − | + | | scope="row" | DZDYF | |
|surface gradient y | |surface gradient y | ||
|1 | |1 | ||
| Line 49: | Line 49: | ||
{| border="1" | {| border="1" | ||
|+Fire variables on atm grid (outputs to atm model) | |+Fire variables on atm grid (outputs to atm model) | ||
| − | + | | scope="col" | Variable name | |
| − | + | | scope="col" | Description | |
| − | + | | scope="col" | Unit | |
|- | |- | ||
| − | + | | scope="row" | RTHFRTEN | |
|temperature tendency | |temperature tendency | ||
|K/s | |K/s | ||
|- | |- | ||
| − | + | | scope="row" | RQVFRTEN | |
|humidity tendency | |humidity tendency | ||
| | | | ||
| Line 65: | Line 65: | ||
{| border="1" | {| border="1" | ||
|+Diagnostics | |+Diagnostics | ||
| − | + | | scope="col" | Variable name | |
| − | + | | scope="col" | Description | |
| − | + | | scope="col" | Unit | |
|- | |- | ||
| − | + | | scope="row" | AVG_FUEL_FRAC | |
|fuel remaining averaged to atmospheric grid | |fuel remaining averaged to atmospheric grid | ||
|1 | |1 | ||
|- | |- | ||
| − | + | | scope="row" | GRNHFX | |
|heat flux from ground fire | |heat flux from ground fire | ||
|W/m<sup>2 | |W/m<sup>2 | ||
|- | |- | ||
| − | + | | scope="row" | GRNQFX | |
|moisture flux from ground fire | |moisture flux from ground fire | ||
|W/m<sup>2 | |W/m<sup>2 | ||
|- | |- | ||
| − | + | | scope="row" | CANHFX | |
|heat flux from crown fire | |heat flux from crown fire | ||
|W/m<sup>2 | |W/m<sup>2 | ||
|- | |- | ||
| − | + | | scope="row" | CANQFX | |
|moisture flux from crown fire | |moisture flux from crown fire | ||
|W/m<sup>2 | |W/m<sup>2 | ||
|- | |- | ||
| − | + | | scope="row" | UAH | |
|wind at fire_wind_heigh | |wind at fire_wind_heigh | ||
|m/s | |m/s | ||
|- | |- | ||
| − | + | | scope="row" | VAH | |
|wind at fire_wind_heigh | |wind at fire_wind_heigh | ||
|m/s | |m/s | ||
| Line 101: | Line 101: | ||
{| border="1" | {| border="1" | ||
|+Sfire variables on fire grid(also using inputs: zs,z_at_w,dz8w,nfuel_cat,zsf) | |+Sfire variables on fire grid(also using inputs: zs,z_at_w,dz8w,nfuel_cat,zsf) | ||
| − | + | | scope="col" | Variable name | |
| − | + | | scope="col" | Description | |
| − | + | | scope="col" | Unit | |
|- | |- | ||
| − | + | | scope="row" | TIGN_G | |
|ignition time on ground | |ignition time on ground | ||
|s | |s | ||
|- | |- | ||
| − | + | | scope="row" | LFN | |
|level function | |level function | ||
|1 | |1 | ||
|- | |- | ||
| − | + | | scope="row" | FUEL_FRAC | |
|fuel remaining | |fuel remaining | ||
|1 | |1 | ||
|- | |- | ||
| − | + | | scope="row" | FMC_G | |
|fuel moisture contents | |fuel moisture contents | ||
|1 | |1 | ||
|- | |- | ||
| − | + | | scope="row" | FIRE_AREA | |
|fraction of cell area on fire | |fraction of cell area on fire | ||
|1 | |1 | ||
|- | |- | ||
| − | + | | scope="row" | UF | |
|fire wind | |fire wind | ||
|m/s | |m/s | ||
|- | |- | ||
| − | + | | scope="row" | VF | |
|fire wind | |fire wind | ||
|m/s | |m/s | ||
|- | |- | ||
| − | + | | scope="row" | FGRNHFX | |
|heat flux from ground fire | |heat flux from ground fire | ||
|W/m<sup>2 | |W/m<sup>2 | ||
|- | |- | ||
| − | + | | scope="row" | FGRNQFX | |
|moisture flux from ground fire | |moisture flux from ground fire | ||
|W/m<sup>2 | |W/m<sup>2 | ||
|- | |- | ||
| − | + | | scope="row" | FCANHFX | |
|heat flux from crown fire | |heat flux from crown fire | ||
|W/m<sup>2 | |W/m<sup>2 | ||
|- | |- | ||
| − | + | | scope="row" | FCANQFX | |
|moisture flux from crown fire | |moisture flux from crown fire | ||
|W/m<sup>2 | |W/m<sup>2 | ||
| Line 153: | Line 153: | ||
{| border="1" | {| border="1" | ||
|+Diagnostics for the actual modeled fire | |+Diagnostics for the actual modeled fire | ||
| − | + | | scope="col" | Variable name | |
| − | + | | scope="col" | Description | |
| − | + | | scope="col" | Unit | |
|- | |- | ||
| − | + | | scope="row" | ROS | |
|rate of spread in the normal direction to the fireline | |rate of spread in the normal direction to the fireline | ||
|m/s | |m/s | ||
|- | |- | ||
| − | + | | scope="row" | FLINEINT | |
|fireline intensity | |fireline intensity | ||
|W/m | |W/m | ||
|- | |- | ||
| − | + | | scope="row" | FLINEINT2 | |
|alternative fireline intensity | |alternative fireline intensity | ||
|J/m/s<sup>2 | |J/m/s<sup>2 | ||
| Line 172: | Line 172: | ||
{| border="1" | {| border="1" | ||
|+Diagnostics for fire risk rating - independent on any actual fire going on | |+Diagnostics for fire risk rating - independent on any actual fire going on | ||
| − | + | | scope="col" | Variable name | |
| − | + | | scope="col" | Description | |
| − | + | | scope="col" | Unit | |
|- | |- | ||
| − | + | | scope="row" | F_ROS0 | |
|base rate of spread in all directions | |base rate of spread in all directions | ||
|m/s | |m/s | ||
|- | |- | ||
| − | + | | scope="row" | F_ROSX | |
|X component of the spread vector driven by wind and slope | |X component of the spread vector driven by wind and slope | ||
|m/s | |m/s | ||
|- | |- | ||
| − | + | | scope="row" | F_ROSY | |
|Y component of the spread vector driven by wind and slope | |Y component of the spread vector driven by wind and slope | ||
|m/s | |m/s | ||
|- | |- | ||
| − | + | | scope="row" | F_ROS | |
|max spread rate in any direction | |max spread rate in any direction | ||
|m/s | |m/s | ||
|- | |- | ||
| − | + | | scope="row" | F_INT | |
|fire reaction intensity for risk rating, without fire | |fire reaction intensity for risk rating, without fire | ||
|J/m<sup>2</sup>/s | |J/m<sup>2</sup>/s | ||
|- | |- | ||
| − | + | | scope="row" | F_LINEINT | |
|Byram fireline intensity for risk rating, without fire | |Byram fireline intensity for risk rating, without fire | ||
|J/m/s | |J/m/s | ||
|- | |- | ||
| − | + | | scope="row" | F_LINEINT2 | |
|alternative fireline intensity for risk rating, without fire" | |alternative fireline intensity for risk rating, without fire" | ||
|J/m/s<sup>2 | |J/m/s<sup>2 | ||
| Line 208: | Line 208: | ||
{| border="1" | {| border="1" | ||
|+Constant data arrays | |+Constant data arrays | ||
| − | + | | scope="col" | Variable name | |
| − | + | | scope="col" | Description | |
| − | + | | scope="col" | Unit | |
|- | |- | ||
| − | + | | scope="row" | FXLONG | |
|longitude of midpoints of fire cells | |longitude of midpoints of fire cells | ||
|degrees | |degrees | ||
|- | |- | ||
| − | + | | scope="row" |FXLAT | |
|latitude of midpoints of fire cells | |latitude of midpoints of fire cells | ||
|degrees | |degrees | ||
|- | |- | ||
| − | + | | scope="row" |FUEL_TIME | |
|fuel | |fuel | ||
| | | | ||
|- | |- | ||
| − | + | | scope="row" |BBB | |
|fuel | |fuel | ||
| | | | ||
|- | |- | ||
| − | + | | scope="row" |PHISC | |
|fuel | |fuel | ||
| | | | ||
|- | |- | ||
| − | + | | scope="row" |PHIWC | |
|fuel | |fuel | ||
| | | | ||
|- | |- | ||
| − | + | | scope="row" |R_0 | |
|fuel | |fuel | ||
| | | | ||
|- | |- | ||
| − | + | | scope="row" |FGIP | |
|fuel | |fuel | ||
| | | | ||
|- | |- | ||
| − | + | | scope="row" |FZ0 | |
|fuel roughness height | |fuel roughness height | ||
| | | | ||
|- | |- | ||
| − | + | | scope="row" |FWH | |
|fuel fire wind height | |fuel fire wind height | ||
| | | | ||
|- | |- | ||
| − | + | | scope="row" |ISCHAP | |
|fuel | |fuel | ||
| | | | ||
|} | |} | ||
| + | |||
| + | |||
| + | === Fire intensities === | ||
| + | {| border="1" | ||
| + | |+ | ||
| + | | scope="col" | Intensity (Unit) | ||
| + | | scope="col" | Description | ||
| + | | scope="col" | Definition | ||
| + | | scope="col" | Implementation | ||
| + | | scope="col" | Depends on rates | ||
| + | |- | ||
| + | | scope="row" | Reaction (J/m<sup>2</sup>/s) | ||
| + | |the heat release rate per unit area of the front | ||
| + | | I<sub>R=H(w<sub>0</sub>-w<sub>n</sub>)/&tau<sub>R | ||
| + | | | ||
Revision as of 08:30, 29 September 2011
- Back to the WRF-SFIRE user guide.
Introduction
The fire mesh is 2D. Every atmosphere cell is divided into sr_x by sr_y fire cells. The submesh ratios sr_x and sr_y are specified in the file namelist.input. These values are not stored in the NetCDF files, but can be computed from the dimension sizes.
sr_x=west_east_subgrid/west_east_stag = west_east_subgrid/(west_east + 1) sr_y=south_north_subgrid/south_north_stag = south_north_subgrid/(south_north + 1)
For historical reasons, the fire grid dimensions in the output files are larger than what is actually used by the code internally. The extra space is at the end of the variables of size sr_x in x and sr_y in y. The following is an example of python code for correctly reading FGRNHFX from the file wrfout.
from netCDF4 import Dataset
f=Dataset('wrfout','r')
sr_x=len(f.dimensions['west_east_subgrid'])/(len(f.dimensions['west_east'])+1)
sr_y=len(f.dimensions['south_north_subgrid'])/(len(f.dimensions['south_north'])+1)
fgrnhfx=f.variables['FGRNHFX']
fgrnhfx=fgrnhfx[...,:-sr_y,:-sr_x]
Variables on the fire mesh are located at the centers of the fire mesh cells of a 2D fire mesh.
List of variables
The authoritative information can be always found in the Registry.
| Variable name | Description | Unit |
| NFUEL_CAT | fuel data | |
| ZSF | height of surface above sea level | m |
| DZDXF | surface gradient x | 1 |
| DZDYF | surface gradient y | 1 |
| Variable name | Description | Unit |
| RTHFRTEN | temperature tendency | K/s |
| RQVFRTEN | humidity tendency |
| Variable name | Description | Unit |
| AVG_FUEL_FRAC | fuel remaining averaged to atmospheric grid | 1 |
| GRNHFX | heat flux from ground fire | W/m2 |
| GRNQFX | moisture flux from ground fire | W/m2 |
| CANHFX | heat flux from crown fire | W/m2 |
| CANQFX | moisture flux from crown fire | W/m2 |
| UAH | wind at fire_wind_heigh | m/s |
| VAH | wind at fire_wind_heigh | m/s |
| Variable name | Description | Unit |
| TIGN_G | ignition time on ground | s |
| LFN | level function | 1 |
| FUEL_FRAC | fuel remaining | 1 |
| FMC_G | fuel moisture contents | 1 |
| FIRE_AREA | fraction of cell area on fire | 1 |
| UF | fire wind | m/s |
| VF | fire wind | m/s |
| FGRNHFX | heat flux from ground fire | W/m2 |
| FGRNQFX | moisture flux from ground fire | W/m2 |
| FCANHFX | heat flux from crown fire | W/m2 |
| FCANQFX | moisture flux from crown fire | W/m2 |
| Variable name | Description | Unit |
| ROS | rate of spread in the normal direction to the fireline | m/s |
| FLINEINT | fireline intensity | W/m |
| FLINEINT2 | alternative fireline intensity | J/m/s2 |
| Variable name | Description | Unit |
| F_ROS0 | base rate of spread in all directions | m/s |
| F_ROSX | X component of the spread vector driven by wind and slope | m/s |
| F_ROSY | Y component of the spread vector driven by wind and slope | m/s |
| F_ROS | max spread rate in any direction | m/s |
| F_INT | fire reaction intensity for risk rating, without fire | J/m2/s |
| F_LINEINT | Byram fireline intensity for risk rating, without fire | J/m/s |
| F_LINEINT2 | alternative fireline intensity for risk rating, without fire" | J/m/s2 |
| Variable name | Description | Unit |
| FXLONG | longitude of midpoints of fire cells | degrees |
| FXLAT | latitude of midpoints of fire cells | degrees |
| FUEL_TIME | fuel | |
| BBB | fuel | |
| PHISC | fuel | |
| PHIWC | fuel | |
| R_0 | fuel | |
| FGIP | fuel | |
| FZ0 | fuel roughness height | |
| FWH | fuel fire wind height | |
| ISCHAP | fuel |
Fire intensities
| Intensity (Unit) | Description | Definition | Implementation | Depends on rates |
| Reaction (J/m2/s) | the heat release rate per unit area of the front | IR=H(w0-wn)/&tauR |