ET-SCI cold-wave family index. Length in days of the longest
cold-wave event in each year (see ck_cwn() for the cold-wave
definition).
Arguments
- tmin
Numeric vector of daily minimum temperatures (degrees C).
- dates
Date vector of the same length as
tmax. Must contain data covering the reference period.- ref_start, ref_end
Integer. Reference period boundary years (inclusive). Defaults to 1961 and 1990.
- min_spell
Integer. Minimum spell length in days (default 3, the ET-SCI standard).
Details
Note: the same letters CWD also denote the ETCCDI Consecutive Wet
Days precipitation index, which is unrelated and is implemented in
ck_wet_days(). These are two different indices that share an
acronym in the climate-extremes literature.
Examples
set.seed(1)
dates <- seq(as.Date("1961-01-01"), as.Date("1991-12-31"), by = "day")
tmin <- 5 + 8 * sin(2 * pi * as.integer(format(dates, "%j")) / 365) +
rnorm(length(dates))
tail(ck_cwd(tmin, dates))
#> period value index unit
#> 26 1986-01-01 0 cwd days
#> 27 1987-01-01 0 cwd days
#> 28 1988-01-01 3 cwd days
#> 29 1989-01-01 0 cwd days
#> 30 1990-01-01 0 cwd days
#> 31 1991-01-01 0 cwd days