Bias correction

Quantile-quantile mapping (Themeßl et al. 2012, Grenier et al. 2015) is provided with ClimateTools.jl through the function qqmap.

qqmap(obs::ClimGrid, ref::ClimGrid, fut::ClimGrid; method::String="Additive", detrend::Bool=true, window::Int=15, rankn::Int=50, thresnan::Float64=0.1, keep_original::Bool=false, interp = Linear(), extrap = Flat())

Quantile-quantile mapping is a computational costly function. An alternative is to build a single transfer function over a domain.

qqmaptf(obs::ClimGrid, ref::ClimGrid; partition::Float64 = 1.0, method::String="Additive", window::Int64=15, rankn::Int64=50, interp = Linear(), extrap = Flat())

where partition is the fraction of grid points that will be considered in the construction of the transfer function. qmaptf returns ITP an Interpolation type. ITP then can be provided to the following qqmap method, which apply the transfer function ITP to values in ClimGrid fut.

qqmap(fut::ClimGrid, ITP; method::String="Additive")

More information can be found in these references.

Themeßl, Matthias Jakob, Andreas Gobiet, and Georg Heinrich. 2012. “Empirical-Statistical Downscaling and Error Correction of Regional Climate Models and Its Impact on the Climate Change Signal.” Climatic Change 112 (2). Springer: 449–68.

Grenier, Patrick, Ramón de Elía, and Diane Chaumont. 2015. “Chances of Short-Term Cooling Estimated from a Selection of CMIP5-Based Climate Scenarios during 2006-2035 over Canada.” Journal of Climate, January 2015. American Meteorological Society. doi:10.1175/JCLI-D-14-00224.1.