AccumulationExceedingThreshold {CSIndicators}

Accumulation of a variable when Exceeding (not exceeding) a Threshold

Description

The accumulation (sum) of a variable in the days (or time steps) that the variable is exceeding (or not exceeding) a threshold during a period. The threshold provided must be in the same units than the variable units, i.e. to use a percentile as a scalar, the function Threshold or QThreshold may be needed. Providing mean daily temperature data, the following agriculture indices for heat stress can be obtained by using this function:

• 'GDD', Summation of daily differences between daily average temperatures and 10°C between April 1st and October 31st.

Usage

AccumulationExceedingThreshold(
  data,
  threshold,
  op = ">",
  diff = FALSE,
  dates = NULL,
  start = NULL,
  end = NULL,
  time_dim = "time",
  na.rm = FALSE,
  ncores = NULL
)

Arguments

data

A multidimensional array with named dimensions.

threshold

If only one threshold is used: it can be a multidimensional array with named dimensions. It must be in the same units and with the common dimensions of the same length as parameter 'data'. It can also be a vector with the same length of 'time_dim' from 'data' or a scalar. If we want to use two thresholds: it can be a vector of two scalars, a list of two vectors with the same length of 'time_dim' from 'data' or a list of two multidimensional arrays with the common dimensions of the same length as parameter 'data'. If two thresholds are used, parameter 'op' must be also a vector of two elements.

op

An operator '>' (by default), '<', '>=' or '<='. If two thresholds are used it has to be a vector of a pair of two logical operators: c('<', '>'), c('<', '>='), c('<=', '>'), c('<=', '>='), c('>', '<'), c('>', '<='), c('>=', '<'),c('>=', '<=')).

diff

A logical value indicating whether to accumulate the difference between data and threshold (TRUE) or not (FALSE by default). It can only be TRUE if a unique threshold is used.

dates

A multidimensional array of dates with named dimensions matching the temporal dimensions on parameter 'data'. By default it is NULL, to select aperiod this parameter must be provided.

start

An optional parameter to define 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 define 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 dimension to compute the indicator. By default, it is set to 'time'. It can only indicate one time dimension.

na.rm

A logical value indicating whether to ignore NA values (TRUE) or not (FALSE).

ncores

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

Value

A multidimensional array with named dimensions containing the aggregated values with dimensions of the input parameter 'data' except the dimension where the indicator has been computed.

Examples

# Assuming data is already (tasmax + tasmin)/2 - 10
data <- array(rnorm(5 * 3 * 214 * 2, mean = 25, sd = 3),
                   c(memb = 5, sdate = 3, time = 214, lon = 2)) 
GDD <- AccumulationExceedingThreshold(data, threshold = 0, start = list(1, 4),
                                     end = list(31, 10))