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Setting Up Burn Periods for NTFB
The duration of modeled burning for each day of Near-Term Fire Behavior projection is known as the model's 'burn period'. Each projection date in NTFB must have at least one burn period.
The default burn period in NTFB is 24 hours; however, modeling a fire overnight is generally not advised. NTFB, like FARSITE, has a tendency to over-predict overnight fire spread. For this reason, most analysts shorten the duration that the modeled fire is allowed to burn each day.
A good starting point for calibration is to estimate the hours that the real-world fire is actively spreading (with head and flanking fire), and then buffer that by an hour or two on each end. Doing so approximates the periods of slower burning and overnight backing fire growth. For example, If the fire you are modeling is actively burning (or anticipated to actively burn) from 1400 to 1800, a reasonable burn period for a first calibration run might be from 1300 to 1900.
Though it is not likely to be a common scenario, more than one burn period can be assigned for each day, if needed.
To set up burn periods for NTFB:
- From the Analysis List, select the NTFB analysis that you want to set up burn periods for.
- Click View Information. The General Information page appears for the selected analysis.
- Scroll down to the Burn Periods section, and if necessary, click the down arrow to expand the section. Four burn periods appear as a default.
- Modify the start and end hours (military time) for each analysis date using the active burn time for the actual fire.
- Modify the number of burn periods.
- To add more burn periods, click Add. The page refreshes and adds a burn period to the bottom of the list.
- To delete a burn period, select the period you want to delete, then click Delete. The the selected burn period is removed and the page refreshes.
- Click Save.
- You can continue to tweak the analysis parameters until the analysis is run.
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