1 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 FWI System FBP System FOP System New Zealand Fire Danger Rating System AFM System WeatherRisk of Ignition TopographyFuels NZFDRS Reduction Readiness Recovery Fire Management Applications Response 2

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 3

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 Weather Topography Fuel 4

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 FWI System FBP System FOP System New Zealand Fire Danger Rating System AFM System WeatherRisk of Ignition TopographyFuels NZFDRS 5

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 Wind Speed Temperature Relative Humidity Rainfall Temperature Rainfall 6

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) 7

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 Wind Speed Temperature Relative Humidity Rainfall Temperature Rainfall 8

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 9 Temperature Relative Humidity Wind Speed Rainfall Wind Speed Temperature Relative Humidity Rainfall Temperature Rainfall

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 10 Temperature Relative Humidity Wind Speed Rainfall Wind Speed Temperature Relative Humidity Rainfall Temperature Rainfall

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 11

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 12

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 13

Fire Danger Class Limits Fire Danger Class Fire Intensity (kW/m) Control Requirements L< 10Ground crews with hand tools M10-500Ground crews with back- pack pumps H Water under pressure and/or heavy machinery VH Aircraft using chemical fireretardants E> 4000Very difficult if not impossible to control 14

NZ Fire Danger Class Criteria Temperature Relative Humidity Wind Speed Rainfall Wind Speed Temperature Relative Humidity Rainfall Temperature Rainfall ScrublandGrasslandForest Grass Degree of Curing (%) Wind speed FFMC ISI BUIDoC% 15

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) 16

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! 17

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 18