ck_cwd: Cold-Wave Duration (CWD, ET-SCI)

In climatekit: Unified Climate Indices for Temperature, Precipitation, and Drought

Cold-Wave Duration (CWD, ET-SCI)

Description

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).

Usage

ck_cwd(tmin, dates, ref_start = 1961L, ref_end = 1990L, min_spell = 3L)

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.

Value

A data frame with columns period, value, index, and unit.

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))

climatekit documentation built on May 9, 2026, 5:08 p.m.