CSIndicators (version 1.1.2)

WindPowerDensity: Wind power density on multidimensional array objects

Description

Wind Power Density computes the wind power that is available for extraction per square meter of swept area.

It is computed as 0.5*ro*wspd^3. As this function is non-linear, it will give inaccurate results if used with period means.

Usage

WindPowerDensity(
  wind,
  ro = 1.225,
  dates = NULL,
  start = NULL,
  end = NULL,
  time_dim = "time",
  ncores = NULL
)

Value

An array with the same dimensions as wind, containing Wind Power Density expressed in W/m^2.

Arguments

wind

A multidimensional array, vector or scalar with instantaneous wind speeds expressed in m/s.

ro

A scalar, or alternatively a multidimensional array with the same dimensions as wind, with the air density expressed in kg/m^3. By default it takes the value 1.225, the standard density of air at 15ºC and 1013.25 hPa.

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 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 dimension to compute the indicator. By default, it is set to 'time'. 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 for temporal subsetting.

Author

Llorenç Lledó,

Examples

wind <- array(rweibull(n = 32100, shape = 2, scale = 6), 
             c(member = 5, sdate = 3, time = 214, lon = 2, lat = 5))
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)
WPD <- WindPowerDensity(wind, dates = Dates, start = list(21, 4), 
                       end = list(21, 6))