CST_RFSlope {CSTools}

RainFARM spectral slopes from a CSTools object

Description

This function computes spatial spectral slopes from a CSTools object to be used for RainFARM stochastic precipitation downscaling method and accepts a CSTools object (of the class 's2dv_cube') as input.

Usage

CST_RFSlope(data, kmin = 1, time_dim = NULL, ncores = NULL)

Arguments

data

An object of the class 's2dv_cube', containing the spatial precipitation fields to downscale. The data object is expected to have an element named $data with at least two spatial dimensions named "lon" and "lat" and one or more dimensions over which to average these slopes, which can be specified by parameter time_dim.

kmin

First wavenumber for spectral slope (default kmin=1).

time_dim

String or character array with name(s) of dimension(s) (e.g. "ftime", "sdate", "member" ...) over which to compute spectral slopes. If a character array of dimension names is provided, the spectral slopes will be computed as an average over all elements belonging to those dimensions. If omitted one of c("ftime", "sdate", "time") is searched and the first one with more than one element is chosen.

ncores

Is an integer that indicates the number of cores for parallel computations using multiApply function. The default value is one.

Value

CST_RFSlope() returns spectral slopes using the RainFARM convention (the logarithmic slope of k*|A(k)|^2 where A(k) are the spectral amplitudes). The returned array has the same dimensions as the exp element of the input object, minus the dimensions specified by lon_dim, lat_dim and time_dim.

Author(s)

Jost von Hardenberg - ISAC-CNR, [e-mail]

Examples

exp <- 1 : (2 * 3 * 4 * 8 * 8)
dim(exp) <- c(dataset = 1, member = 2, sdate = 3, ftime = 4, lat = 8, lon = 8)
lon <- seq(10, 13.5, 0.5)
lat <- seq(40, 43.5, 0.5)
coords <- list(lon = lon, lat = lat)
data <- list(data = exp, coords = coords)
class(data) <- 's2dv_cube'
slopes <- CST_RFSlope(data)