ck_cwa: Cold-Wave Amplitude (CWA)

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

Cold-Wave Amplitude (CWA)

Description

ET-SCI cold-wave family index. mode = "excess" (default) returns the peak (threshold - Tmin) across cold-wave days, expressed as a positive magnitude. mode = "absolute" returns the minimum raw Tmin across cold-wave days (the coldest event-day value). Returns NA for years with no cold waves.

Usage

ck_cwa(
  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.

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_cwa(tmin, dates))

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