fire_season {cffdrs}

Fire Season Start and End

Description

fire_season calculates the start and end fire season dates for a given weather station. The current method used in the function is based on three consecutive daily maximum temperature thresholds (Wotton and Flannigan 1993, Lawson and Armitage 2008). This function process input from a single weather station.

An important aspect to consider when calculating Fire Weather Index (FWI) System variables is a definition of the fire season start and end dates (Lawson and Armitage 2008). If a user starts calculations on a fire season too late in the year, the FWI System variables may take too long to reach equilibrium, thus throwing off the resulting indices. This function presents two method of calculating these start and end dates, adapted from Wotton and Flannigan (1993), and Lawson and Armitage (2008). The approach taken in this function starts the fire season after three days of maximum temperature greater than 12 degrees Celsius. The end of the fire season is determined after three consecutive days of maximum temperature less than 5 degrees Celsius. The two temperature thresholds can be adjusted as parameters in the function call. In regions where temperature thresholds will not end a fire season, it is possible for the fire season to span multiple years, in this case setting the multi.year parameter to TRUE will allow these calculations to proceed.

This fire season length definition can also feed in to the overwinter DC calculations (overwinter_drought_code). View the cffdrs package help files for an example of using the fire_season, overwinter_drought_code, and fwi functions in conjunction.

Usage

fire_season(
  input,
  fs.start = 12,
  fs.end = 5,
  method = "WF93",
  consistent.snow = FALSE,
  multi.year = FALSE
)

Arguments

input

A data.frame containing input variables of including the date/time and daily maximum temperature. Variable names have to be the same as in the following list, but they are case insensitive. The order in which the input variables are entered is not important either.

yr	(required)	Year of the observations
mon	(required)	Month of the observations
day	(required)	Day of the observations
tmax	(required)	Maximum Daily Temperature (degrees C)
snow_depth	(optional)	Is consistent snow data in the input?

.

fs.start

Temperature threshold (degrees C) to start the fire season (default=12)

fs.end

Temperature threshold (degrees C) to end the fire season (default=5)

method

Method of fire season calculation. Options are "wf93"" or "la08" (default=WF93)

consistent.snow

Is consistent snow data in the input? (default=FALSE)

multi.year

Should the fire season span multiple years? (default=FALSE)

Value

fire_season returns a data frame of season and start and end dates. Columns in data frame are described below.

Primary FBP output includes the following 8 variables:

yr

Year of the fire season start/end date

mon

Month of the fire season start/end date

day

Day of the fire season start/end date

fsdatetype

Fire season date type (values are either "start" or "end")

date

Full date value

Author(s)

Alan Cantin, Xianli Wang, Mike Wotton, and Mike Flannigan

References

Wotton, B.M. and Flannigan, M.D. (1993). Length of the fire season in a changing climate. Forestry Chronicle, 69, 187-192.

https://www.ualberta.ca/~flanniga/publications/1993_Wotton_Flannigan.pdf

Lawson, B.D. and O.B. Armitage. 2008. Weather guide for the Canadian Forest Fire Danger Rating System. Nat. Resour. Can., Can. For. Serv., North. For. Cent., Edmonton, AB https://cfs.nrcan.gc.ca/pubwarehouse/pdfs/29152.pdf

See Also

fwi, overwinter_drought_code

Examples

library(cffdrs)
# The standard test data:
data("test_wDC")
print(head(test_wDC))
## Sort the data:
input <- with(test_wDC, test_wDC[order(id, yr, mon, day), ])

# Using the default fire season start and end temperature
# thresholds:
a_fs <- fire_season(input[input$id == 1, ])

# Check the result:
a_fs

#    yr mon day fsdatetype
# 1 1999   5   4      start
# 2 1999   5  12        end
# 3 1999   5  18      start
# 4 1999   5  25        end
# 5 1999   5  30      start
# 6 1999  10   6        end
# 7 2000   6  27      start
# 8 2000  10   7        end

# In the resulting data frame, the fire season starts
# and ends multiple times in the first year. It is up to the user for how
# to interpret this.

# modified fire season start and end temperature thresholds
a_fs <- fire_season(input[input$id == 1, ], fs.start = 10, fs.end = 3)
a_fs
#    yr mon day fsdatetype
# 1 1999   5   2      start
# 2 1999  10  20        end
# 3 2000   6  16      start
# 4 2000  10   7        end
# select another id value, specify method explicitly
b_fs <- fire_season(input[input$id == 2, ], method = "WF93")
# print the calculated fire_season
b_fs
#   yr mon day fsdatetype
# 1 1980   4  21      start
# 2 1980   9  19        end
# 3 1980  10   6      start
# 4 1980  10  16        end
# 5 1981   5  21      start
# 6 1981  10  13        end