TotalSpellTimeExceedingThreshold {CSIndicators}R Documentation

Total Spell Time Exceeding Threshold

Description

The number of days (when daily data is provided) that are part of a spell (defined by its minimum length e.g. 6 consecutive days) that exceed (or not exceed) a threshold are calculated with TotalSpellTimeExceedingThreshold. This function allows to compute indicators widely used in Climate Services, such as:

WSDIWarm Spell Duration Index that count the total number of days with at least 6 consecutive days when the daily temperature maximum exceeds its 90th percentile. This function requires the data and the threshold to be in the same units. The 90th percentile can be translate into absolute values given a reference dataset using function Threshold or the data can be transform into probabilites by using function AbsToProbs. See section @examples.

Usage

TotalSpellTimeExceedingThreshold(
  data,
  threshold,
  spell,
  op = ">",
  dates = NULL,
  start = NULL,
  end = NULL,
  time_dim = "time",
  ncores = NULL
)

Arguments

data

a multidimensional array with named dimensions.

threshold

a multidimensional array with named dimensions in the same units as parameter 'data' and with the common dimensions of the element 'data' of the same length. If timd_dim is in the dimension (with the same length as data), the comparison will be done day by day.

spell

a scalar indicating the minimum length of the spell.

op

a opartor '>' (by default), '<', '>=' or '<='.

dates

a vector of dates or a multidimensional array of dates with named dimensions matching the dimensions on parameter 'data'. By default it is NULL, to select a period this parameter must be provided.

start

an optional parameter to defined the initial date of the period to select from the data by providing a list of two elements: the initial date of the period and the initial month of the period. By default it is set to NULL and the indicator is computed using all the data provided in data.

end

an optional parameter to defined the final date of the period to select from the data by providing a list of two elements: the final day of the period and the final month of the period. By default it is set to NULL and the indicator is computed using all the data provided in data.

time_dim

a character string indicating the name of the function to compute the indicator. By default, it is set to 'ftime'. More than one dimension name matching the dimensions provided in the object data$data can be specified.

ncores

an integer indicating the number of cores to use in parallel computation.

Details

This function considers NA values as the end of the spell. For a different behaviour consider to modify the 'data' input by substituting NA values by values exceeding the threshold.

Value

A multidimensional array with named dimensions.

See Also

[Threshold()] and [AbsToProbs()].

Examples

data <- array(rnorm(120), c(member = 1, sdate = 2, time = 20, lat = 4))
threshold <- array(rnorm(4), c(lat = 4))
total <- TotalSpellTimeExceedingThreshold(data, threshold, spell = 6)

[Package CSIndicators version 0.0.1 Index]