% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/heatwave.R
\name{ck_cwa}
\alias{ck_cwa}
\title{Cold-Wave Amplitude (CWA)}
\usage{
ck_cwa(
  tmin,
  dates,
  ref_start = 1961L,
  ref_end = 1990L,
  min_spell = 3L,
  mode = c("excess", "absolute")
)
}
\arguments{
\item{tmin}{Numeric vector of daily minimum temperatures (degrees C).}

\item{dates}{Date vector of the same length as \code{tmax}. Must contain
data covering the reference period.}

\item{ref_start, ref_end}{Integer. Reference period boundary years
(inclusive). Defaults to 1961 and 1990.}

\item{min_spell}{Integer. Minimum spell length in days (default 3,
the ET-SCI standard).}

\item{mode}{One of \code{"excess"} (default) or \code{"absolute"}. See details.}
}
\value{
A data frame with columns \code{period}, \code{value}, \code{index}, and \code{unit}.
}
\description{
ET-SCI cold-wave family index. \code{mode = "excess"} (default) returns
the peak (threshold - Tmin) across cold-wave days, expressed as a
positive magnitude. \code{mode = "absolute"} returns the minimum raw
Tmin across cold-wave days (the coldest event-day value). Returns
\code{NA} for years with no cold waves.
}
\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))
}
