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Fire Growth Modelling at Multiple Scales. Kerry Anderson Canadian Forest Service. Fire Growth Modelling at Multiple Scales. Introduction Weather and fire activity can be thought of occurring on different time and space scales.

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Fire Growth Modelling at Multiple Scales

Kerry Anderson

Canadian Forest Service

fire growth modelling at multiple scales

Fire Growth Modelling at Multiple Scales

Introduction

Weather and fire activity can be thought of occurring on different time and space scales.

Forecasting at each of these scales has its individual practical and physical limitations.

scales

year

Jet

Stream

month

week

Longwaves

Fronts

day

SYNOPTIC

Cyclones

Thunderstorms

Time

hour

Cumulus

Clouds

Scales

MESO

min

MICRO

Turbulence

sec

1 mm

1 m

1 km

1000 km

Length

scales1

year

Jet

Stream

month

Campaign

Fires

week

Longwaves

Holdover

Fires

Class E

Fires

(> 200 ha)

Fronts

day

SYNOPTIC

Cyclones

Thunderstorms

Time

hour

Detected

Fires

(~0.1ha)

Cumulus

Clouds

Scales

MESO

Fire Whirls

min

Ignitions

MICRO

Turbulence

sec

1 mm

1 m

1 km

1000 km

Length

fire growth modelling at multiple scales1

Fire Growth Modelling at Multiple Scales

Introduction

Fire growth modelling can fall into three scales depending on weather forecasting ability:

Short-range: 1-2 days

Medium-range: 3-7 days

Long-range: 8+ days

fire growth modelling at multiple scales2

Fire Growth Modelling at Multiple Scales

Short-range

Introduction

As the run time increases, the model becomes less deterministic and more probabilistic.

Medium-range

Long-range

deterministic

weather-based

detailed

probabilistic

climate -based

generalized

fire growth modelling at multiple scales3

Fire Growth Modelling at Multiple Scales

The Models

This presentation shows a fire growth modelling system designed to run consecutively over three time scales.

The models are designed so that they may be run in sequence, with the results of one model initializing the subsequent model run.

fire growth modelling at multiple scales4

Fire Growth Modelling at Multiple Scales

The Probabilistic Fire Analysis System is a suite of models designed to capture the transition across multiple scales.

The Models

fire growth modelling at multiple scales5

Fire Growth Modelling at Multiple Scales

USFS Farsite and the

Canadian Prometheus

Short-range Fire Growth

are examples of operational, deterministic, short-range fire growth models.

fire growth modelling at multiple scales6

Fire Growth Modelling at Multiple Scales

Short-range Fire Growth

The short-range model is a deterministic, sixteen -point fire growth model that uses hourly weather.

fire growth modelling at multiple scales7

Fire Growth Modelling at Multiple Scales

Short-range Fire Growth

Hourly weather is obtained from numerical weather models.

fire growth modelling at multiple scales8

Fire Growth Modelling at Multiple Scales

Short-range Fire Growth

Fire locations are determined using NOAA/AVHRR and MODIS hot spot data.

fire growth modelling at multiple scales9

Fire Growth Modelling at Multiple Scales

Short-range predictions are produced for the next 24 to 48 hours.

Short-range Fire Growth

fire growth modelling at multiple scales10

Fire Growth Modelling at Multiple Scales

Short-range predictions are currently being presented through the CWFIS interactive web-page and GoogleEarth.

Short-range Fire Growth

August 15, 2013

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Fire Growth Modelling at Multiple Scales

Medium-range Fire Growth

The medium-range model uses the same deterministic fire growth but uses more general, daily weather information.

Day Two

Tmax: 20

Tmin 10

Rhnoon 35

POP: 0%

Day Three

Tmax: 22

Tmin 8

Rhnoon 25

POP: 0%

Day Four

Tmax: 21

Tmin 19

Rhnoon 30

POP: 0%

Day Five

Tmax: 18

Tmin 14

Rhnoon 60

POP: 30%

fire growth modelling at multiple scales12

Fire Growth Modelling at Multiple Scales

Daily forecasts are combined with diurnal trend models to produce hourly weather profiles.

Medium-range Fire Growth

fire growth modelling at multiple scales13

Fire Growth Modelling at Multiple Scales

Uncertainty in the forecast can be introduced as perturbations

(e.g. Temp + 1oC),

each producing a new weather series.

Medium-range Fire Growth

fire growth modelling at multiple scales14

Fire Growth Modelling at Multiple Scales

Medium-range Fire Growth

Ensemble forecasts are produced by running the model through a range of weather conditions creating probable fire perimeters.

Temp + 1 oC

RH + 5%

WD + 10o

WS + 3 kmh

fire growth modelling at multiple scales15

Fire Growth Modelling at Multiple Scales

Medium-range Fire Growth

Probable fire perimeters can be further enhanced by introducing the probability of precipitation.

rain

no rain

fire growth modelling at multiple scales16

Current hotspot

Old hotspot

(now extinguished)

11%

33%

55%

77%

100%

Fire Growth Modelling at Multiple Scales

Case studies show an improvement in fire growth predictions when using an ensemble approach.

Medium-range Fire Growth

fire growth modelling at multiple scales17

Fire Growth Modelling at Multiple Scales

Currently we are examining CMC ensemble products for use in medium-range fire growth predictions.

Medium-range Fire Growth

fire growth modelling at multiple scales18

Fire Growth Modelling at Multiple Scales

Long-range Fire Growth

The long-range fire growth model is probabilistic and is based upon climatology.

Such models are based on probabilities and thus output is represented as probable fire extents.

fire growth modelling at multiple scales19

p(t) = p (t)  P (t)

spread

survival

Fire Growth Modelling at Multiple Scales

Long-range Fire Growth

Long term fire growth from one location to another within a given time period isthe probability that the fire will spread across the distance before a fire-stopping rain event occurs.

fire growth modelling at multiple scales20

Fire Growth Modelling at Multiple Scales

Pspread(r > ro) = e-λ r

Long-range Fire Growth

Probability of spread is calculated by assuming the rate of spread follows an exponential distribution

where 1/λ = mean rate of spread

o

fire growth modelling at multiple scales21

Fire Growth Modelling at Multiple Scales

Mean rates of spread can be calculated for each fuel type, each month, each direction.

These are similar to wind roses but for the rate of spread for each fuel type.

Long-range Fire Growth

Mean rates of spread in C2 fuel type for August

fire growth modelling at multiple scales22

Fire Growth Modelling at Multiple Scales

Probability of survival can be modelled using the DMC.

If the DMC drops below an extinction value, the fire is assumed to go out.

Long-range Fire Growth

fire growth modelling at multiple scales23

Fire Growth Modelling at Multiple Scales

Probability of survival is solved using Markov Chains and DMC.

As time progresses, the probability of survival drops to zero.

Long-range Fire Growth

fire growth modelling at multiple scales24

Fire Growth Modelling at Multiple Scales

Long-range Fire Growth

The model calculates the probabilities of spread and of survival and combines them spatially to produce a probable fire extents map.

40%

50%

50%

60%

Spread

Survival

Extents

fire growth modelling at multiple scales25

Historic

Fire

Perimeter

10%

30%

50%

0

50

100

150

200

250 km

Fire Growth Modelling at Multiple Scales

Long-range Fire Growth

Comparisons with historical fires indicate the model produces realistic results

…but is difficult to validate this way.

fire growth modelling at multiple scales26

10%

10%

30%

30%

50%

50%

c) Long-range model probabiltiy

a) 40 simulated fires

b) 40 simulation probability

Fire Growth Modelling at Multiple Scales

Long-range Fire Growth

The long-range model predictions were compared with distributions of fire perimeters predicted by repeated simulations using the hourly-based, deterministic fire-growth model.

The study showed a close agreement between the long-range model and the deterministic model.

fire growth modelling at multiple scales27

Fire Growth Modelling at Multiple Scales

Combined Prediction

The models are designed so that they may be run in sequence, with the results of one model initializing the subsequent model run.

Short-range: day 1 to day 2

Medium-range: day 3 to day 7

Long-range: day 8 to day 21

fire growth modelling at multiple scales28

Fire Growth Modelling at Multiple Scales

Medium

Long

Combined Prediction

The results of one model are used to initialize the subsequent model run.

Short

2 days

7 days

21 days

fire growth modelling at multiple scales29

Fire Growth Modelling at Multiple Scales

Long-range Fire Growth

The long-range model PFAS was used in BC during the 2009 and 2010 fire seasons.

Terrain

Fuels

15 day

Fire Growth Projection (Prescribed Fire Analysis System)

_____Current fire perimeter (approx 76 000 ha)

_____ 15 day area at risk (approx 180 000 ha) (50 % probability)

_____30 day area at risk (approx 317 000 ha) (50 % probability)

30 day

Predictions were used to assess modified response decisions.

fire growth modelling at multiple scales30

Fire Growth Modelling at Multiple Scales

Long-range Fire Growth

In 2009, PFAS predictions were used to assess modified response decisions made on 37 fires.

In 2010, this was done on xxx fires.

In all cases, PFAS was used to supplement the decision support decision made by fire suppression officers. In a few cases, the predictions triggered a reassessment of the suppression response plan.

fire growth modelling at multiple scales31

Fire Growth Modelling at Multiple Scales

Conclusions

As forest protection agencies re-evaluate the role of fire in the landscape and its ecological benefits, as they face the prospect of excessive fuel build up resulting from years of fire exclusion policies, and as they contend with fiscal constraints, these agencies must start looking at possible fire growth over extended periods.

The methods presented through these models may serve as a foundation for such evaluation.