TotalTimeExceedingThreshold: Total Time of a variable Exceeding (not exceeding) a...

In CSIndicators: Climate Services' Indicators Based on Sub-Seasonal to Decadal Predictions

Total Time of a variable Exceeding (not exceeding) a Threshold

Description

The Total Time of a variable exceeding (or not) a Threshold. It returns the total number of days (if the data provided is daily, or the corresponding units of the data frequency) that a variable is exceeding a threshold during a period. The threshold provided must be in the same units as the variable units, i.e. to use a percentile as a scalar, the function AbsToProbs or QThreshold may be needed (see examples). Providing maximum temperature daily data, the following agriculture indices for heat stress can be obtained by using this function:

• 'SU35', Total count of days when daily maximum temperatures exceed 35°C in the seven months from the start month given (e.g. from April to October for start month of April).

• 'SU36', Total count of days when daily maximum temperatures exceed 36 between June 21st and September 21st.

• 'SU40', Total count of days when daily maximum temperatures exceed 40 between June 21st and September 21st.

• 'Spr32', Total count of days when daily maximum temperatures exceed 32 between April 21st and June 21st.

Usage

TotalTimeExceedingThreshold(
  data,
  threshold,
  op = ">",
  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('>=', '<=')).
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 total number of the corresponding units of the data frequency that a variable is exceeding a threshold during a period with dimensions of the input parameter 'data' except the dimension where the indicator has been computed.

Examples

data <- array(rnorm(5 * 3 * 214 * 2)*23,
             c(member = 5, sdate = 3, time = 214, lon = 2)) 
Dates <- c(seq(as.Date("01-05-2000", format = "%d-%m-%Y"), 
              as.Date("30-11-2000", format = "%d-%m-%Y"), by = 'day'),
          seq(as.Date("01-05-2001", format = "%d-%m-%Y"), 
              as.Date("30-11-2001", format = "%d-%m-%Y"), by = 'day'),
          seq(as.Date("01-05-2002", format = "%d-%m-%Y"), 
              as.Date("30-11-2002", format = "%d-%m-%Y"), by = 'day'))
dim(Dates) <- c(sdate = 3, time = 214)
DOT <- TotalTimeExceedingThreshold(data, threshold = 23, dates = Dates,
                                  start = list(21, 4), end = list(21, 6))

CSIndicators documentation built on Nov. 20, 2023, 5:07 p.m.