Operational fire danger rating system in New Zealand and prediction of fire season severity
Jim Salinger National Institute of Water & Atmospheric Research, Auckland, NZ Grant Pearce Scion Research, Christchurch, NZ [email protected]
Fire Danger Rating Workshop, Edmonton, Alberta, 14-16 July Outline
• Background • New Zealand fire danger rating system • Fire weather monitoring network • Seasonal climate prediction • Factors causing high seasonal fire risk • Seasonal fire climate outlooks • Conclusions Background
• 3000 “rural” fires per year, burning about 6500 ha – fire numbers increasing at 200-300 per year – escapes from land clearing burns common, arson increasing
5000 20000
4500 Forest 18000 Scrub 4000 Grass 16000 No. fires 3500 14000
3000 12000
2500 10000
2000 8000 Number of firesNumber Area burned (ha) 1500 6000
1000 4000
500 2000
0 0
3 9 0 4 5 8 1 2 0 0 6 7 / /9 9 3 4 / / 0 0 / /9 9 5 6 2 / / 0 8 9 / /9 9 7 8 3 4 / 8 0 1 / /9 9 9 0 0 5 6 8 9 2 3 / /9 9 1 2 0 0 9 9 9 9 4 5 / /0 0 0 0 0 1 9 9 9 9 6 7 / 0 0 0 1 1 9 9 9 9 8 9 / 2 2 1 1 9 9 9 9 0 1 2 2 1 1 9 9 9 0 1 1 9 9 0 0 (Source: NRFA Annual Return of Fires) 1 1 0 0 1 2 0 2 2 Background – Major Fires
• 1945/46 central North Island – 140,000 ha total, including 13,000 ha pine plantation • 1955 Balmoral (Canterbury) – 3100 ha pine plantation • 1983 Ohinewairua (CNI) – 15 000 ha of tussock + beech • 1999 Alexandra – 9600 ha in two grass fires • 2000 Blenheim – 7000 ha in two grass fires • 2003/04 Canterbury – major fires at West Melton, Flock Hill, Dunsandel and Mt Somers Background
Weather and climate
• combined effects result in increased fire risk • significant fires often occur
under nor’west conditions Weather map associated with the – hot, dry and windy Berwick Forest Fire, 26 February 1995 • fire season typically Oct-Apr • fires can occur at any time of year NZ Fire Danger Rating System
• adopted Canadian Fire Weather Index New Zealand (FWI) System in 1980 Fire Danger Rating System
Risk of Weather Topography Fuels • subsequent adaptation of other Ignition Canadian components FWI • describes “probability of a fire starting, System spreading and doing damage” FOP AFM FBP • principal use for notifying the public System System System
• also information to support fire NZFDRS management decision-making Fire Management Applications Prevention Detection Presuppression Suppression NZ Fire Danger Rating System
Rainfall Fire Relative Humidity Rainfall Weather Wind Speed Wind Relative Humidity Rainfall Observations Temperature Speed Temperature Temperature
Fine Fuel Duff Moisture • core component of NZFDRS Fuel Drought Code Moisture Moisture Code Code Codes (DC) • based solely on weather inputs (FFMC) (DMC) • provides numerical ratings Initial Spread Build Up of fuel moisture content and fire Index (ISI) Index (BUI) Fire Behaviour behaviour potential Indexes
• indicates relative ease of ignition, Fire Weather fuel availability, fire spread and Index (FWI) difficulty of control • basis for fire danger class criteria for Forest, Grassland and Scrubland Scrubland Grassland Forest Fire Danger Fire Danger Fire Danger Class Class Class Fire weather monitoring network • daily (1200 NZST) observations – temperature – relative humidity – wind speed (and direction) – 24-hour rainfall • 160+ stations across country – MetService/NIWA (45) – Rural Fire Authorities (115) • collected and archived by the National Rural Fire Authority – used to calculate and map daily fire danger ratings – http://nrfa.fire.org.nz/fire_weather Fire weather monitoring network Fire weather monitoring network Fire weather monitoring network Seasonal climate prediction
Weather predictable for 1-2 weeks
• Day-by-day detail, individual events • Future determined by weather today
Climate predictable for 3-6 months
• Average picture, distribution of events • Ocean the key, often far from New Zealand • Modulates weather over a season • Weather today almost irrelevant Seasonal climate prediction
ENSO: Changing the odds
Sea temperature difference from average
El Niño Conditions Summer 1997/98 • Based in the tropical Pacific ocean • Large influence on New Zealand, on average • Westerly winds, ocean and land temperatures Seasonal climate prediction ENSO: Changing the odds
El Niño effect, % La Niña effect, %
Summer rainfall ly a m o n a d in W
aly anom Wind
But average changes do not tell the full story Seasonal climate prediction Observations
ENSO Climate State patterns ENSO forecasts Forecasts Global Climatology Expert forecasts ENSO Assessment Analogue Climatology selection Background MSLP, R Regional, seasonal forecasts & rain (WWW)
Tailored products Factors causing high fire risk Anticyclones
To the north west To the west To the south east Factors causing high fire risk Anticyclones
Southwest flow Westerly flow Over the centre Seasonal fire climate outlooks AUCKLAND EAST - FAR NORTH COROMANDEL
• High to northwest •El Niño • High to northwest • Westerlies AUCKLAND WEST - • High to the WAIKATO southeast Seasonal Fire Weather Climate Outlook
Expected climate pattern
District seasonal outlook End of November 2003 Impacts of Future Climate
Changes in the average number of days of Very High and Extreme (VH+E) Forest fire danger (%) occurring over the full calendar year Conclusions • NZ Fire Danger Rating system is based on the Canadian system • Uses solely weather inputs • Provides numerical ratings, used for fire danger class criteria for Forest, Grassland and Scrubland • Operates and serves NZ needs well – and is a valuable daily input to the management of forest and rural lands in NZ • Over 160 + stations are in place to allow daily monitoring of fire weather • Seasonal climate prediction has been used in NZ as a fire management tool • Six general climate patterns increase fire risk • Further research ongoing in the development of management tools