Vertical wind interpolation - Revision history

Adamko: /* Options */

2025-09-11T00:31:32Z

Options

← Older revision		Revision as of 00:31, 11 September 2025
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	The interpolation mode is controlled by the values of the variables '''fire_wind_log_interp''' and '''fire_use_windrf''' in the file [https://github.com/jbeezley/wrf-fire/blob/e062dbf62b7591e71a486a7c512efd75e48ed9a1/wrfv2_fire/test/em_fire/small/namelist.input#L180 '''namelist.input''']:		The interpolation mode is controlled by the values of the variables '''fire_wind_log_interp''' and '''fire_use_windrf''' in the file [https://github.com/jbeezley/wrf-fire/blob/e062dbf62b7591e71a486a7c512efd75e48ed9a1/wrfv2_fire/test/em_fire/small/namelist.input#L180 '''namelist.input''']:
	<pre>		<pre>
	fire_wind_log_interp = 1, ! 1 = from fuel ~~categores~~, 2= roughness piecewise constant from atm, 3=bilinear from atm, 4=on atmosphere mesh		fire_wind_log_interp = 1, ! 1 = from fuel categories, 2= roughness piecewise constant from atm, 3=bilinear from atm, 4=on atmosphere mesh
	fire_use_windrf=2, ! if fire_wind_log_interp.ne.4: 0=ignore wind reduction factors, 1=multiply, 2=use to set fwh, 3=adjust fwh for z0		fire_use_windrf=2, ! if fire_wind_log_interp.ne.4: 0=ignore wind reduction factors, 1=multiply, 2=use to set fwh, 3=adjust fwh for z0
	</pre>		</pre>

Jmandel: {{users guide}}

2011-08-02T05:15:12Z

← Older revision		Revision as of 05:15, 2 August 2011
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			{{users guide}}
	==Vertical log interpolation and wind reduction factors==		==Vertical log interpolation and wind reduction factors==
	The wind speed that enters the spread rate formula is found by vertical interpolation to a specified height '''fwh''', sometimes called ''midflame height'', using the ideal logarithmic wind profile: the wind speed at height '''z''' is assumed to be proportional to log '''z/z<sub>0</sub>''', where '''z<sub>0</sub>''' is the ''roughness height'' (clearly, this is the height where the wind speed is zero). The special logarithmic interpolation we use preserves such functions just like linear interpolation preserves linear functions. The numbers '''fwh''' and '''z<sub>0</sub>''' need to be known at every point of the fire mesh.		The wind speed that enters the spread rate formula is found by vertical interpolation to a specified height '''fwh''', sometimes called ''midflame height'', using the ideal logarithmic wind profile: the wind speed at height '''z''' is assumed to be proportional to log '''z/z<sub>0</sub>''', where '''z<sub>0</sub>''' is the ''roughness height'' (clearly, this is the height where the wind speed is zero). The special logarithmic interpolation we use preserves such functions just like linear interpolation preserves linear functions. The numbers '''fwh''' and '''z<sub>0</sub>''' need to be known at every point of the fire mesh.

Jmandel: /* Vertical log interpolation and wind reduction factors */

2011-08-01T09:26:49Z

Vertical log interpolation and wind reduction factors

← Older revision		Revision as of 09:26, 1 August 2011
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	The wind speed that enters the spread rate formula is found by vertical interpolation to a specified height '''fwh''', sometimes called ''midflame height'', using the ideal logarithmic wind profile: the wind speed at height '''z''' is assumed to be proportional to log '''z/z<sub>0</sub>''', where '''z<sub>0</sub>''' is the ''roughness height'' (clearly, this is the height where the wind speed is zero). The special logarithmic interpolation we use preserves such functions just like linear interpolation preserves linear functions. The numbers '''fwh''' and '''z<sub>0</sub>''' need to be known at every point of the fire mesh.		The wind speed that enters the spread rate formula is found by vertical interpolation to a specified height '''fwh''', sometimes called ''midflame height'', using the ideal logarithmic wind profile: the wind speed at height '''z''' is assumed to be proportional to log '''z/z<sub>0</sub>''', where '''z<sub>0</sub>''' is the ''roughness height'' (clearly, this is the height where the wind speed is zero). The special logarithmic interpolation we use preserves such functions just like linear interpolation preserves linear functions. The numbers '''fwh''' and '''z<sub>0</sub>''' need to be known at every point of the fire mesh.

	In [[BEHAVE]], the wind is measured at ~~the~~ 20ft (6.096m) and log interpolated to the midflame height. The interpolation is the same as multiplying the wind speed by a given ''wind reduction factor~~'' '''windrf'~~'' ([http://www.firemodels.org/downloads/behaveplus/publications/Baughman_and_Albini_1980_6thConFireForMet_EstMidflamWind.pdf Baughman and Albini, 1980]).		In [[BEHAVE]], the wind is measured at 20ft (6.096m) and log interpolated to the midflame height. The interpolation is the same as multiplying the wind speed by a given ''wind reduction factor'' ([http://www.firemodels.org/downloads/behaveplus/publications/Baughman_and_Albini_1980_6thConFireForMet_EstMidflamWind.pdf Baughman and Albini, 1980]), which we denote by '''windrf'''.

	See [http://www.geosci-model-dev.net/4/591/2011/gmd-4-591-2011.html Mandel et al. 2011] Sec. 5.2 for more details.		See [http://www.geosci-model-dev.net/4/591/2011/gmd-4-591-2011.html Mandel et al. 2011] Sec. 5.2 for more details.

Jmandel: /* Data input */

2011-08-01T09:21:54Z

Data input

← Older revision		Revision as of 09:21, 1 August 2011
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	==Data input==		==Data input==

	In WRF, the roughness height '''z0''' is specified by the surface model in land use. This is typically taken from file [https://github.com/jbeezley/wrf-fire/blob/e062dbf62b7591e71a486a7c512efd75e48ed9a1/wrfv2_fire/run/LANDUSE.TBL LANDUSE.TBL]. The values of the midflame height '''fwh''', the fuel roughness height '''fz0''', ~~and~~ the wind reduction factors '''windrf''' for each fuel category, and the BEHAVE height '''fire_wind_height''', are specified in the file [https://github.com/jbeezley/wrf-fire/blob/e062dbf62b7591e71a486a7c512efd75e48ed9a1/wrfv2_fire/test/em_fire/small/namelist.fire '''namelist.fire'''] as a part of the fuel properties. If these values are not given in the file, the [https://github.com/jbeezley/wrf-fire/blob/e062dbf62b7591e71a486a7c512efd75e48ed9a1/wrfv2_fire/phys/module_fr_sfire_phys.F#L93 defaults] in the code apply.		In WRF, the roughness height '''z0''' is specified by the surface model in land use. This is typically taken from file [https://github.com/jbeezley/wrf-fire/blob/e062dbf62b7591e71a486a7c512efd75e48ed9a1/wrfv2_fire/run/LANDUSE.TBL LANDUSE.TBL]. The values of the midflame height '''fwh''', the fuel roughness height '''fz0''', the wind reduction factors '''windrf''' for each fuel category, and the BEHAVE height '''fire_wind_height''', are specified in the file [https://github.com/jbeezley/wrf-fire/blob/e062dbf62b7591e71a486a7c512efd75e48ed9a1/wrfv2_fire/test/em_fire/small/namelist.fire '''namelist.fire'''] as a part of the fuel properties. If these values are not given in the file, the [https://github.com/jbeezley/wrf-fire/blob/e062dbf62b7591e71a486a7c512efd75e48ed9a1/wrfv2_fire/phys/module_fr_sfire_phys.F#L93 defaults] in the code apply.

	Note that the roughness height '''z0''' from land use and '''fz0''' will be generally different, and besides they are given on different meshes.		Note that the roughness height '''z0''' from land use and '''fz0''' will be generally different, and besides they are given on different meshes.

Jmandel: /* Interpolation to different heights on the fire mesh */

2011-08-01T09:20:38Z

Interpolation to different heights on the fire mesh

← Older revision		Revision as of 09:20, 1 August 2011
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	The adjustment of '''fwh''' is done by first [https://github.com/jbeezley/wrf-fire/blob/e062dbf62b7591e71a486a7c512efd75e48ed9a1/wrfv2_fire/phys/module_fr_sfire_atm.F#L809 computing] the wind reduction factor when going from '''fire_wind_height''' to the given height '''fwh''' with the given roughness '''fz0''', then [https://github.com/jbeezley/wrf-fire/blob/e062dbf62b7591e71a486a7c512efd75e48ed9a1/wrfv2_fire/phys/module_fr_sfire_atm.F#L809 changing] '''fwh''' to the value that corresponds to the same wind reduction factor but with the interpolated '''z0'''.		The adjustment of '''fwh''' is done by first [https://github.com/jbeezley/wrf-fire/blob/e062dbf62b7591e71a486a7c512efd75e48ed9a1/wrfv2_fire/phys/module_fr_sfire_atm.F#L809 computing] the wind reduction factor when going from '''fire_wind_height''' to the given height '''fwh''' with the given roughness '''fz0''', then [https://github.com/jbeezley/wrf-fire/blob/e062dbf62b7591e71a486a7c512efd75e48ed9a1/wrfv2_fire/phys/module_fr_sfire_atm.F#L809 changing] '''fwh''' to the value that corresponds to the same wind reduction factor but with the interpolated '''z0'''.

			==Diagnostics==

			You can use function [https://github.com/jbeezley/wrf-fire/blob/e062dbf62b7591e71a486a7c512efd75e48ed9a1/other/Matlab/vis3d/vprofile.m '''vprofile'''] in [[Matlab]] ('''cd em_fire''', '''matlab''', help '''vprofile''') to view the resulting wind profiles and the computed value of '''fwh'''. See [[How to visualize vertical profiles from WRF in Matlab]] for details.

	==References==		==References==

Jmandel: /* Options */

2011-08-01T09:20:12Z

Options

← Older revision		Revision as of 09:20, 1 August 2011
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	fire_use_windrf=2, ! if fire_wind_log_interp.ne.4: 0=ignore wind reduction factors, 1=multiply, 2=use to set fwh, 3=adjust fwh for z0		fire_use_windrf=2, ! if fire_wind_log_interp.ne.4: 0=ignore wind reduction factors, 1=multiply, 2=use to set fwh, 3=adjust fwh for z0
	</pre>		</pre>

	You can use function [https://github.com/jbeezley/wrf-fire/blob/e062dbf62b7591e71a486a7c512efd75e48ed9a1/other/Matlab/vis3d/vprofile.m '''vprofile'''] in [[Matlab]] ('''cd em_fire''', '''matlab''', help '''vprofile''') to view the resulting wind profiles and the computed value of '''fwh'''. See [[How to visualize vertical profiles from WRF in Matlab]] for details.

	Supported combinations of the options are listed below. In particular, do not use '''fire_use_windrf'''=1, which is for experiments only.		Supported combinations of the options are listed below. In particular, do not use '''fire_use_windrf'''=1, which is for experiments only.

Jmandel: /* Options */

2011-08-01T09:19:47Z

Options

← Older revision		Revision as of 09:19, 1 August 2011
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	You can use function [https://github.com/jbeezley/wrf-fire/blob/e062dbf62b7591e71a486a7c512efd75e48ed9a1/other/Matlab/vis3d/vprofile.m '''vprofile'''] in [[Matlab]] ('''cd em_fire''', '''matlab''', help '''vprofile''') to view the resulting wind profiles and the computed value of '''fwh'''. See [[How to visualize vertical profiles from WRF in Matlab]] for details.		You can use function [https://github.com/jbeezley/wrf-fire/blob/e062dbf62b7591e71a486a7c512efd75e48ed9a1/other/Matlab/vis3d/vprofile.m '''vprofile'''] in [[Matlab]] ('''cd em_fire''', '''matlab''', help '''vprofile''') to view the resulting wind profiles and the computed value of '''fwh'''. See [[How to visualize vertical profiles from WRF in Matlab]] for details.

	Supported options ~~and their combinations~~ are listed below. In particular, do not use '''fire_use_windrf'''=1, which is for experiments only.		Supported combinations of the options are listed below. In particular, do not use '''fire_use_windrf'''=1, which is for experiments only.

	===Interpolation to common height and wind reduction factors===		===Interpolation to common height and wind reduction factors===

Jmandel: /* Interpolation to different heights on the fire mesh */

2011-08-01T09:18:30Z

Interpolation to different heights on the fire mesh

← Older revision		Revision as of 09:18, 1 August 2011
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	===Interpolation to different heights on the fire mesh===		===Interpolation to different heights on the fire mesh===

	The following group of combinations of options controls the interpolation by the wind reduction factor '''windrf'''; '''fwh''' is not used~~. variables, and by rounding errors~~.		The following group of combinations of options controls the interpolation by the wind reduction factor '''windrf'''; '''fwh''' is not used.

	* '''fire_wind_log_interp'''=1, '''fire_use_windrf'''=2: use the roughness height '''fz0''' from fuel categories, ignore '''fwh''' and [https://github.com/jbeezley/wrf-fire/blob/e062dbf62b7591e71a486a7c512efd75e48ed9a1/wrfv2_fire/phys/module_fr_sfire_atm.F#L786 set it automatically] to the height that corresponds to the given '''windrf'''.		* '''fire_wind_log_interp'''=1, '''fire_use_windrf'''=2: use the roughness height '''fz0''' from fuel categories, ignore '''fwh''' and [https://github.com/jbeezley/wrf-fire/blob/e062dbf62b7591e71a486a7c512efd75e48ed9a1/wrfv2_fire/phys/module_fr_sfire_atm.F#L786 set it automatically] to the height that corresponds to the given '''windrf'''.
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	* '''fire_wind_log_interp'''=3, '''fire_use_windrf'''=2: the same, but using roughness height '''z0''' interpolated from land use as piecewise bilinear, ignore '''fz0'''.		* '''fire_wind_log_interp'''=3, '''fire_use_windrf'''=2: the same, but using roughness height '''z0''' interpolated from land use as piecewise bilinear, ignore '''fz0'''.

	The above options will produce similar results as the interpolation to common height and using wind reduction factors; the only difference is from the wind not obeying the log profile exactly. In particular, if the first WRF level is above the '''fire_wind_height''' (of 6.096m, which is usually the case), these three option will give ''the same result as the interpolation on the atmospheric mesh and multiplication by the wind reduction factors'', except for slight differences caused by a different technique used for the interpolation of atmospheric		The above options will produce similar results as the interpolation to common height and using wind reduction factors; the only difference is from the wind not obeying the log profile exactly. In particular, if the first WRF level is above the '''fire_wind_height''' (of 6.096m, which is usually the case), these three option will give ''the same result as the interpolation on the atmospheric mesh and multiplication by the wind reduction factors'', except for slight differences caused by a different technique used for the interpolation of the atmospheric variables, and by rounding errors.

	The combinations of options below control the interpolation by the midflame height '''fwh''', and all three will again produce similar results; '''windrf''' is not used.		The combinations of options below control the interpolation by the midflame height '''fwh''', and all three will again produce similar results; '''windrf''' is not used.

Jmandel: /* Interpolation to different heights on the fire mesh */

2011-08-01T09:17:57Z

Interpolation to different heights on the fire mesh

← Older revision		Revision as of 09:17, 1 August 2011
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	===Interpolation to different heights on the fire mesh===		===Interpolation to different heights on the fire mesh===

	The following group of combinations of options controls the interpolation by the wind reduction factor '''windrf'''; '''fwh''' is not used. These options will produce similar results as the interpolation to common height and using wind reduction factors; the only difference is from the wind not obeying the log profile exactly. In particular, if the first WRF level is above the '''fire_wind_height''' (of 6.096m, which is usually the case), these three option will give ''the same result as the interpolation on the atmospheric mesh and multiplication by the wind reduction factors'', except for slight differences caused by a different technique used for the interpolation of atmospheric variables, and by rounding errors.		The following group of combinations of options controls the interpolation by the wind reduction factor '''windrf'''; '''fwh''' is not used. variables, and by rounding errors.

	* '''fire_wind_log_interp'''=1, '''fire_use_windrf'''=2: use the roughness height '''fz0''' from fuel categories, ignore '''fwh''' and [https://github.com/jbeezley/wrf-fire/blob/e062dbf62b7591e71a486a7c512efd75e48ed9a1/wrfv2_fire/phys/module_fr_sfire_atm.F#L786 set it automatically] to the height that corresponds to the given '''windrf'''.		* '''fire_wind_log_interp'''=1, '''fire_use_windrf'''=2: use the roughness height '''fz0''' from fuel categories, ignore '''fwh''' and [https://github.com/jbeezley/wrf-fire/blob/e062dbf62b7591e71a486a7c512efd75e48ed9a1/wrfv2_fire/phys/module_fr_sfire_atm.F#L786 set it automatically] to the height that corresponds to the given '''windrf'''.
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	* '''fire_wind_log_interp'''=3, '''fire_use_windrf'''=2: the same, but using roughness height '''z0''' interpolated from land use as piecewise bilinear, ignore '''fz0'''.		* '''fire_wind_log_interp'''=3, '''fire_use_windrf'''=2: the same, but using roughness height '''z0''' interpolated from land use as piecewise bilinear, ignore '''fz0'''.

			The above options will produce similar results as the interpolation to common height and using wind reduction factors; the only difference is from the wind not obeying the log profile exactly. In particular, if the first WRF level is above the '''fire_wind_height''' (of 6.096m, which is usually the case), these three option will give ''the same result as the interpolation on the atmospheric mesh and multiplication by the wind reduction factors'', except for slight differences caused by a different technique used for the interpolation of atmospheric
	The combinations of options below control the interpolation by the midflame height '''fwh''', and all three will again produce similar results; '''windrf''' is not used.		The combinations of options below control the interpolation by the midflame height '''fwh''', and all three will again produce similar results; '''windrf''' is not used.

Jmandel: /* Interpolation to different heights on the fire mesh */

2011-08-01T09:17:09Z

Interpolation to different heights on the fire mesh

← Older revision		Revision as of 09:17, 1 August 2011
Line 39:		Line 39:
	===Interpolation to different heights on the fire mesh===		===Interpolation to different heights on the fire mesh===

	The following group of combinations of options controls the interpolation by the wind reduction factor '''windrf'''; '''fwh''' is not used. These options will produce similar results as the interpolation to common height and using wind reduction factors; the only difference is from the wind not obeying the log profile exactly. In particular, if the first WRF level is above the '''fire_wind_height''' (of 6.096m, which is usually the case), these three option will give ''the same result as the interpolation on the atmospheric mesh and multiplication by the wind reduction factors'', except for ~~the~~ differences caused by the ~~different ordering of~~ interpolation of atmospheric variables ~~(horizontally and vertically)~~, and by rounding errors.		The following group of combinations of options controls the interpolation by the wind reduction factor '''windrf'''; '''fwh''' is not used. These options will produce similar results as the interpolation to common height and using wind reduction factors; the only difference is from the wind not obeying the log profile exactly. In particular, if the first WRF level is above the '''fire_wind_height''' (of 6.096m, which is usually the case), these three option will give ''the same result as the interpolation on the atmospheric mesh and multiplication by the wind reduction factors'', except for slight differences caused by a different technique used for the interpolation of atmospheric variables, and by rounding errors.

	* '''fire_wind_log_interp'''=1, '''fire_use_windrf'''=2: use the roughness height '''fz0''' from fuel categories, ignore '''fwh''' and [https://github.com/jbeezley/wrf-fire/blob/e062dbf62b7591e71a486a7c512efd75e48ed9a1/wrfv2_fire/phys/module_fr_sfire_atm.F#L786 set it automatically] to the height that corresponds to the given '''windrf'''.		* '''fire_wind_log_interp'''=1, '''fire_use_windrf'''=2: use the roughness height '''fz0''' from fuel categories, ignore '''fwh''' and [https://github.com/jbeezley/wrf-fire/blob/e062dbf62b7591e71a486a7c512efd75e48ed9a1/wrfv2_fire/phys/module_fr_sfire_atm.F#L786 set it automatically] to the height that corresponds to the given '''windrf'''.