ck_wsdi: Warm Spell Duration Index (WSDI)

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

Warm Spell Duration Index (WSDI)

Description

ETCCDI canonical index WSDI. Annual count of days in spans of at least six consecutive days where daily Tmax exceeds the 90th percentile of the calendar-day distribution from a reference period (default 1961 to 1990). The threshold is computed using a 5-day window centred on each calendar day, pooled across the reference period.

Usage

ck_wsdi(tmax, dates, ref_start = 1961L, ref_end = 1990L, min_spell = 6L)

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 6, the ETCCDI standard).

Details

Days inside qualifying spells are counted into the year they fall in; a spell that crosses a year boundary contributes to both years proportionally. Annual aggregation only.

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_wsdi(tmax, dates))

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