RatioRMS {s2dv}

Compute the ratio between the RMSE of two experiments

Description

Calculate the ratio of the RMSE for two forecasts with the same observation, that is, RMSE(ens, obs) / RMSE(ens.ref, obs). The p-value is provided by a two-sided Fischer test.

Usage

RatioRMS(exp1, exp2, obs, time_dim = "sdate", pval = TRUE, ncores = NULL)

Arguments

exp1

A numeric array with named dimensions of the first experimental data. It must have at least 'time_dim' and have the same dimensions as 'exp2' and 'obs'.

exp2

A numeric array with named dimensions of the second experimental data. It must have at least 'time_dim' and have the same dimensions as 'exp1' and 'obs'.

obs

A numeric array with named dimensions of the observational data. It must have at least 'time_dim' and have the same dimensions as 'exp1' and 'exp2'.

time_dim

A character string of the dimension name along which RMS is computed. The default value is 'sdate'.

pval

A logical value indicating whether to compute the p-value of Ho: RMSE1/RMSE2 = 1 or not. The default value is TRUE.

ncores

An integer indicating the number of cores to use for parallel computation. The default value is NULL.

Value

A list containing the numeric arrays with dimensions identical with 'exp1', 'exp2', and 'obs', except 'time_dim':

$ratiorms

The ratio between the RMSE (i.e., RMSE1/RMSE2).

$p.val

The p-value of the two-sided Fisher test with Ho: RMSE1/RMSE2 = 1. Only exists if 'pval' is TRUE.

Examples

# Compute DJF seasonal means and anomalies.
initial_month <- 11
mean_start_month <- 12
mean_stop_month <- 2                                
sampleData$mod <- Season(sampleData$mod, monini = initial_month, 
                        moninf = mean_start_month, monsup = mean_stop_month)
sampleData$obs <- Season(sampleData$obs, monini = initial_month, 
                        moninf = mean_start_month, monsup = mean_stop_month)
clim <- Clim(sampleData$mod, sampleData$obs)
ano_exp <- Ano(sampleData$mod, clim$clim_exp)
ano_obs <- Ano(sampleData$obs, clim$clim_obs)
# Generate two experiments with 2 and 1 members from the only experiment 
# available in the sample data. Take only data values for a single forecast
# time step.
ano_exp_1 <- ClimProjDiags::Subset(ano_exp, 'member', c(1, 2))
ano_exp_2 <- ClimProjDiags::Subset(ano_exp, 'member', c(3))
ano_exp_1 <- ClimProjDiags::Subset(ano_exp_1, c('dataset', 'ftime'), list(1, 1), drop = 'selected')
ano_exp_2 <- ClimProjDiags::Subset(ano_exp_2, c('dataset', 'ftime'), list(1, 1), drop = 'selected')
ano_obs <- ClimProjDiags::Subset(ano_obs, c('dataset', 'ftime'), list(1, 1), drop = 'selected')
# Compute ensemble mean and provide as inputs to RatioRMS.
rrms <- RatioRMS(MeanDims(ano_exp_1, 'member'), 
                MeanDims(ano_exp_2, 'member'), 
                MeanDims(ano_obs, 'member'))
# Plot the RatioRMS for the first forecast time step.

PlotEquiMap(rrms$ratiorms, sampleData$lon, sampleData$lat, 
           toptitle = 'Ratio RMSE')