ET-SCI cold-wave family index. mode = "excess" (default) returns
the mean of (threshold - Tmin) across cold-wave days, expressed as
a positive magnitude. mode = "absolute" returns the mean raw
Tmin across cold-wave days. Returns NA for years with no cold
waves.
Usage
ck_cwm(
tmin,
dates,
ref_start = 1961L,
ref_end = 1990L,
min_spell = 3L,
mode = c("excess", "absolute")
)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).
- mode
One of
"excess"(default) or"absolute". See details.
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_cwm(tmin, dates))
#> period value index unit
#> 26 1986-01-01 NA cwm °C
#> 27 1987-01-01 NA cwm °C
#> 28 1988-01-01 0.2941017 cwm °C
#> 29 1989-01-01 NA cwm °C
#> 30 1990-01-01 NA cwm °C
#> 31 1991-01-01 NA cwm °C