ck_hwm: Heatwave Magnitude (HWM)

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

Heatwave Magnitude (HWM)

Description

ET-SCI heatwave family index. Reports the mean magnitude of daily Tmax across all heatwave days in the year. mode = "excess" (default) gives the mean of (Tmax - threshold), matching the ET-SCI / climpact convention. mode = "absolute" gives the mean raw Tmax across heatwave days, matching Perkins-Alexander (2013). Returns NA for years with no heatwaves.

Usage

ck_hwm(
  tmax,
  dates,
  ref_start = 1961L,
  ref_end = 1990L,
  min_spell = 3L,
  mode = c("excess", "absolute")
)

Arguments

tmax	Numeric vector of daily maximum 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")
tmax <- 15 + 10 * sin(2 * pi * as.integer(format(dates, "%j")) / 365) +
        rnorm(length(dates))
tail(ck_hwm(tmax, dates))

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