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Analyst-Assisted STFB - What it needs (inputs)

Like other fire behavior models, WFDSS Short-Term Fire Behavior (STFB) requires the following data to perform fire behavior calculations: 

WFDSS provides much of the necessary information to perform fire spread and fire behavior calculations. For Analyst-Assisted STFB, the Fire Behavior Specialist (FBS) can adjust the inputs (weather, winds, and landscape data) as needed. The following table lists the inputs required for the Analyst-Assisted WFDSS Short-Term Fire Behavior model:

Input

Source

Comments

Analysis Name

FBS-defined

Limited to 48 characters, do not use underscores. Can be changed any time before analysis is submitted.

Analysis Date and Time

FBS-defined

This is the "instant in time" for which you want fire behavior outputs.

Conditioning Days

The default conditioning period is 7 days prior to the analysis start date

The FBS can choose the number of days, but should use at least 5 days so 100-hour timelag fuels can be fully "conditioned".

Burn period duration in hours

FBS-defined

The FBS must decide how many hours to use for one burn period (keeping in mind that the same winds and fuel moistures will be used for the entire burn period)

Number of burn periods (days)

FBS-defined (limited to 3)

The FBS must decide how many days of the previously determined burn period will be used for the analysis (keeping in mind that the same winds and fuel moistures will be used for all burn periods)

Foliar Moisture Content

WFDSS Default is 100%

Using 100% foliar moisture is probably adequate to depict a normal year; however, you can modify this value as needed.

Crown Fire Method

Finney (1998) or Scott-Reinhardt (2001)

The Finney crown fire model is the default for the BFB, STFB, NTFB and FSPro models. The Scott and Reinhardt crown fire model is available for use with BFB, STFB and NTFB analysis tools, but not FSPro at this time.

For recent versions of LANDFIRE (2008, 2010) canopy bulk density values were computed to produce more active crown fire when using the Scott and Reinhardt model compared to the Finney crown fire model. You would expect to see slower rates of spread and less fire intensity for predicted passive crown fire when using Finney versus Scott and Reinhardt crown fire models. Whatever crown fire model you choose, it is important to calibrate your simulated fire behavior to observed fire behavior.

Spread Options

Relative Direction from Max.

For Relative Direction from Max, 0 degrees is the default, but you can input whatever value you want to use, depending on what spread direction is of concern.

Spotting Probability

WFDSS default is 0.10. Can be modified by FBS using decimal values from 0-1 (0.40 is 40%).

Enter a decimal value to estimate likelihood of an ember landing on a receptive fuel bed. Higher values increase run time. Base your choice on known fire behavior and as a calibration scaling factor.

Ignition File

FBS-defined

(required)

The FBS chooses the ignition file from a pull down menu.

Barrier File

FBS-defined

(optional)

If needed, FBS chooses the barrier file from the drop-down list.

Remotely Automated Weather Station (RAWS)*

WFDSS selects a RAWS based on the following criteria:

  • identifying the center of the landscape extent
  • calculating the distance from the center to the nearest RAWS(s) using a horizontal/vertical (elevation) algorithm
  • ranking the stations
  • selecting the station that is “closest” and has weather data requisite for fuel moisture conditioning (at least 7 days)

Even though WFDSS selects the "closest" RAWS, the FBS can choose to use a different station, if needed. The FBS can select fewer conditioning days and a different weather station that has weather data requisite for the conditioning days selected.

Loading the RAWS KML (from left-hand menu) into Google Earth can give you insight into which RAWS would be most appropriate for your analysis.

Wind inputs

Wind speed and direction values are populated using National Weather Service (NWS) Forecast Data if the analysis is for the future and WIMS (RAWS data) if the analysis is in the past. 

Gridded winds (default) are generated when the landscape is produced and the wind vectors are created at the same resolution as the landscape.  If gridded winds are not desired the FBS can choose to use static winds (one direction and speed across the landscape) or winds blowing uphill or downhill at a static speed.

Initial Fuel Moisture inputs

Initial fuel moisture values for the beginning of the conditioning period are calculated based on the RAWS locations.

The live fuel moistures (herbaceous and woody) are not affected by fuel moisture conditioning, the FBS should critique these values and change as appropriate.The algorithms for calculating live fuel moistures are known to be poor and they are not "conditioned" like dead fuels. The FBS should always critique these values based on other intelligence from the field, online fuel moisture databases, greenness maps, known fire behavior, or guidance found in the Fire Behavior Field Reference Guide.

Hourly Weather Records

 

 

 

 

The Weather Summary Table displays several days (rows) of daily weather summaries. Hourly data can be viewed and edited by selecting a date and clicking the  'Hourly Records' button below the table. The following hourly inputs are used by STFB:

  • Precipitation amount
  • Temperature
  • Relative Humidity
  • Cloud Cover % (used as part of shading calculation for conditioning fuels)

 

The FBS can change these values as needed.

 

Values that are not editable are not being used by the model (for example, wind speed and direction as those values are unchanging in STFB and set by the FBS in the Wind Inputs).

 

The 'Record Type' column indicates if the data is coming from a RAWS or from forecasted weather.

 

 

 

 

Landscape extent

(extent of analysis area)

FBS-defined

(required)

The FBS will draw the landscape extent (normally no more than 5-6 miles per side) on the Analysis Map page. Remember, for STFB, which is a very short moment in time, you do not typically need to model a large extent since fire conditions typically change by the hour/day.

Landscape Data Sources

WFDSS

  • You can choose to use the default LANDFIRE 2010 1.2.0 landscape data source or select a different data source from the Landscape page.

In addition, the user can modify landscape data layers using the Landscape Editor.

 

* WFDSS chooses the nearby RAWS in the following way:  The ignition location is used as a starting point.  Then, a horizontal/vertical distance algorithm sorts the RAWS stations within a given area.  Next, WFDSS iterates through the list until the first station is found with the requisite fuel moisture / weather information (continuous hourly observations).

In This Section

WFDSS Analyst-Assisted Short-Term Fire Behavior (STFB)

See Also

Analyst-Assisted - STFB - What it is

Analyst-Assisted STFB - What it does (outputs)

Analyst-Assisted STFB - What it means (interpretation)

Analyst-Assisted STFB - Why use it (potential uses)

Analyst-Assisted Asssumptions & Limitations

Reference

Field Descriptions

Glossary Resources

Reports Reference

Spatial Data Reference

Landscape Data Source Reference

Relative Risk Reference

Organization Assessment Reference

Fire Behavior Reference

Decision Editor