QDM: Univariate bias correction via quantile delta mapping

In MBC: Multivariate Bias Correction of Climate Model Outputs

Univariate bias correction via quantile delta mapping

Description

Univariate bias correction based on the quantile delta mapping QDM version of the quantile mapping algorithm from Cannon et al. (2015). QDM constrains model-projected changes in quantiles to be preserved following bias correction by quantile mapping.

Usage

QDM(o.c, m.c, m.p, ratio=FALSE, trace=0.05, trace.calc=0.5*trace,
    jitter.factor=0, n.tau=NULL, ratio.max=2,
    ratio.max.trace=10*trace, ECBC=FALSE, ties='first',
    subsample=NULL, pp.type=7)

Arguments

o.c	vector of observed samples during the calibration period.
m.c	vector of model outputs during the calibration period.
m.p	vector of model outputs during the projected period.
ratio	logical value indicating if samples are of a ratio quantity (e.g., precipitation).
trace	numeric value indicating the threshold below which values of a ratio quantity (e.g., ratio=TRUE) should be considered exact zeros.
trace.calc	numeric value of a threshold used internally when handling of exact zeros; defaults to one half of trace.
jitter.factor	optional strength of jittering to be applied when quantities are quantized.
n.tau	number of quantiles used in the quantile mapping; NULL equals the length of the m.p series.
ratio.max	numeric value indicating the maximum proportional change allowed for ratio quantities below the ratio.max.trace threshold.
ratio.max.trace	numeric value of a trace threshold used to constrain the proportional change in ratio quantities to ratio.max; defaults to ten times trace.
ECBC	logical value indicating whether mhat.p outputs should be ordered according to o.c ranks, i.e., as in the empirical copula-bias correction (ECBC) algorithm.
ties	method used to handle ties when calculating ordinal ranks.
subsample	use subsample draws of size n.tau to calculate empirical quantiles; if NULL, calculate normally.
pp.type	type of plotting position used in quantile.

Value

a list of with elements consisting of:

mhat.c	vector of bias corrected m.c values for the calibration period.
mhat.p	vector of bias corrected m.p values for the projection period.

References

Cannon, A.J., S.R. Sobie, and T.Q. Murdock, 2015. Bias correction of simulated precipitation by quantile mapping: How well do methods preserve relative changes in quantiles and extremes? Journal of Climate, 28:6938-6959. doi:10.1175/JCLI-D-14-00754.1

See Also

MBCp, MBCr, MRS, escore

MBC documentation built on May 3, 2023, 1:16 a.m.