Calculate Burned Area #

FLAM › Calculate Burned Area converts fire probability into expected burned area. It has two modes:

Calibration (Optimize): fits the suppression efficiency q to observed burned area.
Projection (Use existing data): applies a q you calibrated earlier.

Steps #

Parameter file. Click New or Load (a separate .ini from the probability step).
FLAM Parameters. Adjust u_max and m_e, then click Save.
FLAM Calculate Burned Area. Set the inputs and click Run.

Parameter file dialog (burned area)

FLAM Parameters window (burned area)

Parameters #

a   = 0.36·π · u_p² / l_b                 potential area one fire burns in a day (km²)
u_p = g(w) · h(m) · u_max                 rate of spread (km/day)
g(w) = 1 − 0.9·exp(−w² / 2500)            wind effect, w in km/h
h(m) = (1 − min(1, m / m_e))²             moisture effect, m as a fraction
l_b = 1 + 10·(1 − exp(−0.017·w))          length-to-breadth ratio of the fire ellipse

A_burn = P · a · (1 − q)(2 − q) / q²      expected burned area per pixel and day (km²)

Parameter	Default	Meaning
`u_max`	10.8	Maximum rate of spread, km/day (0.45 km/h × 24 h)
`m_e`	0.35	Moisture of extinction: above it, fire doesn’t spread

The GUI window shows h(m) = 1 − B_m². The code uses (1 − B_m)², as shown above.

Inputs #

FLAM Calculate Burned Area window

Field	Description	¶ fills from
Start Date, End Date	Calibration or projection period	Config dates
Probability of Fire (P)	`P` folder from Frequency Probability	`Results/P`
Wind Speed	Daily folder	Daily Wsp
Moisture	Daily folder	Daily Mois
Suppression Efficiency (q)	Optimize or Use existing data	—
Output Folder		Results

Optimize shows these extra fields:

Field	Description	¶ fills from
q time step	Monthly (default): one q per calendar month. Constant: one q for the whole year.	—
Daily Fire Frequency (Opt.)	Observed daily fire occurrence. If set, calibration uses it instead of P as the ignition input.	`Results/Label_Fq_daily`
Burned Area Label	Observed monthly burned area, km² per pixel, files named `<name>_YYYYMM.tif`	`Results/Label_BA_monthly`

Use existing data shows one extra field:

Field	Description
Existing q	Folder that contains only the calibrated `q.tif`, or only `q_01.tif` … `q_12.tif`

How calibration works #

AFEIM first predicts burned area with q = 0.5.
It groups the prediction around each pixel with observed fires.
It solves q so that predicted and observed totals match in each group.
It fills the rest of the map from the nearest group.

With Monthly, each calendar month is calibrated on all years in the period. A month with no observed fires takes q from the nearest month that has fires.

Output #

Folder	Files	Content
`a`	`a_YYYYMMDD.tif`	Potential burned area per fire-day (km²)
`q`	`q.tif` or `q_MM.tif`	Calibrated suppression efficiency (0–1)
	`q_ct.tif` / `q_MM_ct.tif`	q at observed fire locations, before filling the rest of the map
`A_burn`	`A_burn_YYYYMMDD.tif`	Daily burned area (km² per pixel). NoData −9999.

The a folder is reused. If a/ already covers the whole period, the tool doesn’t recalculate it. After you change u_max, m_e, wind or moisture, delete a/ or use a new Output Folder.
To reuse q, copy only q.tif or q_01.tif … q_12.tif into a separate folder, without the *_ct.tif files, and select that folder as Existing q.

Check the result with Graph: plot A_burn against your burned area labels.