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Atmospheric Research 95 (2010) 290–306

Contents lists available at ScienceDirect

Atmospheric Research
j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / a t m o s

Comparison of Canadian Forest Fire Danger Rating System and National Fire
Danger Rating System fire indices derived from Weather Research and
Forecasting (WRF) model data for the June 2005 Interior Alaska wildfires
Nicole Mölders ⁎
University of Alaska Fairbanks, Geophysical Institute and College of Natural Science and Mathematics, Department of Atmospheric Sciences, 903 Koyukuk Drive,
P.O. Box 757320, Fairbanks, AK 99775-7320, USA

a r t i c l e

i n f o

Article history:
Received 1 November 2008
Received in revised form 24 March 2009
Accepted 24 March 2009
Keywords:
Fire indices
WRF
Mesoscale modeling
Fire weather
Polar weather

a b s t r a c t
Standard indices of the National Fire Danger Rating System (NFDRS) and Canadian Forest Fire
Danger Rating System (CFFDRS) are calculated from Weather Research and Forecasting (WRF)
model forecasts and observations in Interior Alaska for June 2005. Fire indices determined from
WRF results of all forecast-leads and the ensemble do not differ statistically significantly from
those calculated from observations. WRF-derived CFFDRS and NFDRS fire indices capture the
temporal evolution of fire indices calculated from observations acceptably. Sensitivity to errors
in meteorological forecasts differs for the various fire indices. Failure to predict a peak does
not necessarily occur at the same time for the various indices within and/or among the two
systems. Predicted buildup-index and spread component capture trends, the time of peaks and
minima most reliably. Overall for the CFFDRS the lowest relative errors exist for fine fuel
moisture content followed by buildup-index while for the NFDRS the lowest relative errors
occur for energy release component followed by burning index. When fire indices are
calculated from meteorological forecasts predicting fire risk and identifying the right site
becomes more difficult as fire risk increases. Fire risk forecast skill depends on meteorological
forecast-lead slightly for energy release rate and ignition component and notably for all
CFFDRS-indices except fine fuel moisture content.
© 2009 Elsevier B.V. All rights reserved.

1. Introduction
The increasing population density and fire activity in the
Arctic and sub-arctic over the last decades (e.g. Stocks et al.,
2000; Podur et al., 2002) demands for relia...
Comparison of Canadian Forest Fire Danger Rating System and National Fire
Danger Rating System re indices derived from Weather Research and
Forecasting (WRF) model data for the June 2005 Interior Alaska wildres
Nicole Mölders
University of Alaska Fairbanks, Geophysical Institute and College of Natural Science and Mathematics, Department of Atmospheric Sciences, 903 Koyukuk Drive,
P.O. Box 757320, Fairbanks, AK 99775-7320, USA
article info abstract
Article history:
Received 1 November 2008
Received in revised form 24 March 2009
Accepted 24 March 2009
Standard indices of the National Fire Danger Rating System (NFDRS) and Canadian Forest Fire
Danger Rating System (CFFDRS) are calculated from Weather Research and Forecasting (WRF)
model forecasts and observations in Interior Alaska for June 2005. Fire indices determined from
WRF results of all forecast-leads and the ensemble do not differ statistically signicantly from
those calculated from observations. WRF-derived CFFDRS and NFDRS re indices capture the
temporal evolution of re indices calculated from observations acceptably. Sensitivity to errors
in meteorological forecasts differs for the various re indices. Failure to predict a peak does
not necessarily occur at the same time for the various indices within and/or among the two
systems. Predicted buildup-index and spread component capture trends, the time of peaks and
minima most reliably. Overall for the CFFDRS the lowest relative errors exist for ne fuel
moisture content followed by buildup-index while for the NFDRS the lowest relative errors
occur for energy release component followed by burning index. When re indices are
calculated from meteorological forecasts predicting re risk and identifying the right site
becomes more difcult as re risk increases. Fire risk forecast skill depends on meteorological
forecast-lead slightly for energy release rate and ignition component and notably for all
CFFDRS-indices except ne fuel moisture content.
© 2009 Elsevier B.V. All rights reserved.
Keywords:
Fire indices
WRF
Mesoscale modeling
Fire weather
Polar weather
1. Introduction
The increasing population density and re activity in the
Arctic and sub-arctic over the last decades (e.g. Stocks et al.,
2000; Podur et al., 2002) demands for reliable regional re risk
assessment. Such assessment requires combining environ-
mental and meteorological conditions that affect initiation
and spread of and efforts to control res into indices reecting
protection needs. Over the last decades, various re danger
rating systems have been developed world wide for different
landscapes (e.g. Fosberg, 1978; Cohen and Deeming, 1985; van
Wagner, 1987; Burgan, 1988; Carlson et al., 20 02 ). Various
comparisons of re danger rating systems illustrate the
extreme importance of considering the regional fuel types
(e.g. Andrews and Bradshaw, 1997; Viegas et al., 1999;
Kleschenko et al., 2004; Tian et al., 2007).
In most of the United States of America, the National Fire
Danger Rating System (NFDRS; Deeming et al., 1977; Cohen
and Deeming, 1985; Burgan, 1988) is used. However, since
1992 Alaskan re managers use the Canadian Forest Fire
Danger Rating System (CFFDRS; van Wagner, 1987) because
the NFDRS only considers two (spruce, tundra) of the various
Alaska fuel types, while the CFFDRS has been developed for a
similar environment like Alaska (cf. e.g. Alexander and Cole,
2001). The advantage of CFFDRS' being more appropriate for
Alaska may quickly turn into a disadvantage when out-of-
state re ghters experienced with the NFDRS, but inexper-
ienced with the CFFDRS are deployed to ght Alaska wildres.
Both the CFFDRS and NFDRS use daily weather data to
determine fuel moisture and combine them into re indices,
but the NFDRS needs more input data than the CFFDRS (see
Atmospheric Research 95 (2010) 290306
Tel.: +1 907 474 7910; fax: +1 907 474 7290.
E-mail address: molders@gi.alaska.edu.
0169-8095/$ see front matter © 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.atmosres.2009.03.010
Contents lists available at ScienceDirect
Atmospheric Research
journal homepage: www.elsevier.com/locate/atmos
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