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Fire Weather Science Fire Weather System Project EcoConnect -Fire Implementation, June 2013

Fire Weather Science Fire Weather System Project EcoConnect -Fire Implementation, June 2013. April 2011. NZ Fire Danger Rating System. NZFDRS derived from Canadian equivalent, the CFFDRS outputs used to assist decision-making across 4 Rs of fire management .

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Fire Weather Science Fire Weather System Project EcoConnect -Fire Implementation, June 2013

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  1. Fire Weather ScienceFire Weather System Project EcoConnect-Fire Implementation, June 2013 April 2011

  2. NZ Fire Danger Rating System • NZFDRS derived from Canadian equivalent, the CFFDRS • outputs used to assist decision-making across 4 Rs of fire management New Zealand Fire Danger Rating System Risk of Weather Topography Fuels Ignition FWI System AFM FOP FBP System System System NZFDRS Fire Management Applications Reduction Readiness Response Recovery

  3. NZFDRS Outputs Fire danger rating: “probability of a fire starting, spreading and doing damage” Fire potential: • indication of expected burning conditions • ease of ignition • potential spread rates • fire intensity • fire size and shape • i.e. fire behaviour

  4. Topography Fuel Weather Vegetation Fire Environment • fire behaviour is the product of the environmental factors which interact with each other and with the fire itself • i.e., the “fire environment”: • topography • fuel • weather

  5. NZ Fire Danger Rating System NZFDRS actually comprised of a number of subsystems: • Fire Weather Index (FWI) System core component • fire behaviour and fire danger classes based on Fire Behaviour Prediction (FBP) System • Fire Occurrence Prediction (FOP) and Accessory Fuel Moisture (AFM) subsystems still under development New Zealand Fire Danger Rating System Risk of Weather Topography Fuels Ignition FWI System AFM FOP FBP System System System NZFDRS

  6. Fire Weather Index (FWI) System • numerical ratings of fuel dryness and potential fire behaviour based solely on weather • i.e. considers weather component only • assumes: • flat ground • uniform fuels • reference fuel type (dead fuel layers in forest floor beneath mature pine stand) • provides relative indicators of fire potential Temperature Relative Humidity Wind Speed Rainfall Temperature Relative Humidity Rainfall Wind Speed Temperature Rainfall

  7. NZ FWI System • adopted from Canada in 1980 • developed in similar fire environment (British Columbia) to NZ (maritime climate, complex terrain, mature pine fuels) • adjusted for use in NZ • season reversal for Southern Hemisphere • daylength drying factors for latitude 40°S • year round calculations • table and computer calculations (incl. new FWSYS)

  8. FWI System • 4 weather inputs: • air temperature, relative humidity, wind speed (& wind direction) and 24-hr accumulated rainfall • measured at 1200 hr NZST • 3 fuel moisture codes • 3 fire behaviour indices • higher code and index values indicate more severe fire potential Temperature Relative Humidity Wind Speed Rainfall Temperature Relative Humidity Rainfall Wind Speed Temperature Rainfall

  9. FWI System – fuel moisture codes Indicators of relative dryness and availability of different fuel layers: Fine Fuel Moisture Code (FFMC) • moisture content of fine fuels • indicates ease of ignition Duff Moisture Code (DMC) • moisture content of loose organic layers & medium woody fuels • involvement of duff & woody fuels Drought Code (DC) • moisture content of compact organic layers & large fuels • involvement of deep organic fuels • indicates potential for mop-up problems, and general seasonal dryness Temperature Relative Humidity Wind Speed Rainfall Temperature Relative Humidity Rainfall Wind Speed Temperature Rainfall

  10. FWI System – fire behaviour indices Relative indicators of potential fire behaviour: Initial Spread Index (ISI) • combines FFMC and wind speed • indicates potential spread rate Buildup Index (BUI) • combines DMC & DC • indicates total fuel consumption Fire Weather Index (FWI) • combines ISI & BUI • indicates potential fire intensity Temperature Relative Humidity Wind Speed Rainfall Temperature Relative Humidity Rainfall Wind Speed Temperature Rainfall

  11. Fire Behaviour Prediction (FBP) System • quantitative estimates of fire behaviour based on fuels, topography and weather • predictions of: • fire spread rates • fuel consumption • fire intensity • fire area & perimeter length • perimeter growth • assumes elliptical fire growth

  12. NZ FBP System • currently 18 identified fuel types • 6 plantation forest • 2 indigenous forest • 2 pasture grassland • 2 crop stubble • 2 tussock grassland • 4 scrub • models for: • available fuel loads • fire spread rates • slope correction factors • various tools now available

  13. NZ Fire Danger Class Criteria • combines FWI & FBP Systems • fire danger classes based on head fire intensity (HFI) • related to suppression effectiveness • models available for Forest, Grassland and Scrubland from FBP System • principal use for notifying the public

  14. Fire Danger Class Limits Fire Fire Control Danger Intensity Requirements Class (kW/m) L < 10 Ground crews with hand tools M 10-500 Ground crews with back- pack pumps H 500-2000 Water under pressure and/or heavy machinery VH 2000-4000 Aircraft using chemical fire retardants E > 4000 Very difficult if not impossible to control

  15. NZ Fire Danger Class Criteria Temperature Relative Humidity Wind Speed Rainfall Temperature Relative Humidity Rainfall Wind Speed Temperature Rainfall Grass Degree of Curing (%) Scrubland Forest Grassland Wind speed ISI ISI FFMC BUI DoC%

  16. New EcoConnect FWSYS Incorporates latest fire behaviour knowledge: • new wind speed-Initial Spread Index (ISI) relationship • reduced effect at high wind speeds (>40 km/h) • new grass degree of curing (DoC%) relationship • allows for limited fire spread below DoC of 50% • also able to incorporate future new science (e.g. FWI, curing)

  17. Daily vs Hourly FWI Values Standard daily FWI System calculations include in-built diurnal forecasting • uses 1200 NZST observations but predicts for peak burning period (1600 hr) • assumes standard diurnal weather pattern • doesn’t always hold, e.g. frontal change, sea breeze • hourly FWIs more accurate • based on actual hourly weather • hourly FWIs in new FWSYS coming!

  18. Conclusions • NZFDRS provides outputs that assist fire management decision-making • NZFDRS is more than just the FWI System • FWI is core, but also FBP and FDCC • Noon daily FWI predicts for mid-afternoon peak burning period (1600 hr) • but assumes standard diurnal cycle, will not always be valid • New EcoConnect-Fire package provides key tool for accessing important fire weather outputs • includes latest science, will be updated as new results produced

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