NBIC-ACS Stage 2 Canadian Forest Fire Weather Index - projected scenarios, 5%, 2% and 1% annual exceedance probabilities

Full description

Canadian Forest Fire Weather Index (FWI) is a fire weather potential index that describes how current weather conditions and recent precipitation patterns could support a landscape fire. While originally was developed for boreal forests, it is now adapted for use in various regions and climates and include other vegetations like grasslands, broadleaf forest and shrublands. FWI calculations are based on Van Wagner & Pickett (1985) and dependent on air temperature, relative humidity, precipitation and wind speed. Returned values start from 0 but don’t have an upper bound constraint. Values above 200 were not anticipated to occur in Canada (Van Wagner (1987) but are regularly reported in Australia. The data provided here is unbounded.
Here we provide predicted upper-bound FWI values across the Australian landscape, defined for a set of annual exceedance probabilities (AEP) modelled using extreme values analysis on more than 43 years of daily data.
The FWI potential rasters represent reasonable worst case extreme conditions. Specifically, the rasters represent the FWI potential for given AEPs of 20%, 10%, 5%, 2% and 1%. These FWI AEPs are based on the projected weather timeseries developed by NBIC using the historical regional weather reanalysis dataset BARRA-R2 [1], and CMIP6-CCAM Regional Climate Models (RCM) [2].
The Regional Climate Models (RCM) considered are:
•\tACCESS ESM 1.5
•\tEC-Earth 3
•\tCMCC ESM2
•\tCNRM ESM 2.1
•\tNCAR CESM2
•\tNorESM2 MM
The future climate change scenarios considered are:
•\tShared Socioeconomic Pathway (SSP) SSP 1-26: Sustainability
•\tSSP 3-70: Regional Rivalry
•\tSSP 3-70: Regional Rivalry, using wind speed from the baseline scenario
The combination of RCMs and future climate change scenarios results in a suite of 18 projected FWI potential datasets.
Lineage: The Canadian Forest Fire Weather Index (FWI) - projected scenario was calculated using the CMIP6-ERA Regional Climate Model data produced with CCAM by CSIRO
(https://dx.doi.org/10.25914/rd73-4m38). Variables used are near surface wind-speed, relative-humidity, air temperature, and rainfall.
Hourly weather variables are sampled or accumulated to 12PM (used as reference hour of the day), then combined using the equations developed by Van Wagner (1987) [1] and after the implementation in Van Wager and Picket (1985) [2] to generate FWI.
Extreme Values Analysis (EVA) is applied on the timeseries 43 years of FWI at 11-degree resolution. EVA is performed based on Peak-Over-Threshold (POT) and Generalised Pareto Distribution (GPD) methods. The modelled probability curve is then sampled at 20%, 10%, 5%, 2% and 1% Annual Exceedance Probabilities.
[1] Van Wagner, C.E. 1987. Development and structure of the Canadian forest fire weather index system. Canadian Forest Service.
[2] Van Wagner, C.E., and T.L. Pickett. 1985. Equations and FORTRAN Program for the Canadian Forest Fire Weather Index System. Ottawa: Canadian Forest Service.