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.
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)a list of with elements consisting of:
vector of bias corrected m.c values for the calibration period.
vector of bias corrected m.p values for the projection period.
vector of observed samples during the calibration period.
vector of model outputs during the calibration period.
vector of model outputs during the projected period.
logical value indicating if samples are of a ratio quantity (e.g., precipitation).
numeric value indicating the threshold below which values of a ratio quantity (e.g., ratio=TRUE) should be considered exact zeros.
numeric value of a threshold used internally when handling of exact zeros; defaults to one half of trace.
optional strength of jittering to be applied when quantities are quantized.
number of quantiles used in the quantile mapping; NULL equals the length of the m.p series.
numeric value indicating the maximum proportional change allowed for ratio quantities below the ratio.max.trace threshold.
numeric value of a trace threshold used to constrain the proportional change in ratio quantities to ratio.max; defaults to ten times trace.
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.
method used to handle ties when calculating ordinal ranks.
use subsample draws of size n.tau to calculate empirical
quantiles; if NULL, calculate normally.
type of plotting position used in quantile.
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
MBCp, MBCr, MRS, escore