Description Usage Arguments Value Details References See Also
Whereas the function fitQmapQUANT
estimates values of the empirical
cumulative distribution function of observed and modeled time series for regularly
spaced quantiles. doQmapQUANT.default_drs
uses these estimates to perform
quantile mapping.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 |
x |
A numeric vector. The values to map. |
fobj |
An object of class |
type |
A character string. Type of interpolation between the fitted transformed values. See details. |
lin_extrapol |
A character string. Type of extrapolation when interpolation is linear. See details. |
spline_method |
A character string. Type of spline, passed to
|
monthly_extremes |
A numeric vector of length two. The first element suggests a monthly minimum value and the second element a monthly maximum value for the mapped output. |
fix_spline |
A character string. See details. |
... |
Additional arguments are ignored. |
type_map |
A character vector. The type of interpolation, extrapolation, and
spline passed to |
monthly_obs_base |
A numeric vector. Base values used to calculate t-scores of
|
A numeric vector of the length of x
. Return values differ among repeated
calls with identical input arguments if jitter correction (using random numbers) is
applied, i.e., type
is “spline”, fix_spline
is
“attempt” and there are values outside the range suggested by
monthly_extremes
.
type
takes one of two possible values
“linear”: linear interpolation using approx
“tricub”: monotonic tricubic spline interpolation using
splinefun
. Splines may result in abnormally high output
values which appears to be due to at least two reasons:
extrapolation errors
huge oscillations in the spline-function which arise from non-monotone
splines (spline_method
is “fmm” or “natural”)
or which arise from numerical instabilities in the exact monotonicity if
spline_method
is “monoH.FC”.
lin_extrapol
is the extrapolation for values of x
that are outside
range(fobj[["par"]]$modq)
. This argument is only in effect if type
is “linear” and takes one of three possible values
“none”: no linear extrapolation is performed, i.e., output of
approx
for type = 2 is return; that is 'values at the
closest data extreme'.
“Boe”: constant extrapolation from Boe et al. 2007
“Thermessl2012CC.QMv1b”: same extrapolation as Boe et al. 2007, but not including three largest/smallest values, from Themessl et al. 2012.
fix_spline
takes one of three values
“none”: No correction to mapped values is applied.
“fail”: If mapped values fall outside the range suggested by
monthly_extremes
, then an error is generated.
“attempt”: The spline-based mapping is repeated up to ten times
where the values of the quantile map fobj
are jittered.
type_map
with “normal_anomalies” represents a 'linear
interpolation with extrapolation following Boe et al. 2007 and a correction using
standard anomalies (i.e. number of standard deviations from the mean) for values
outside the observed quantile map that is based on Tohver et al. 2014 (Appendix A)
Boe, J., L. Terray, F. Habets, and E. Martin. 2007. Statistical and dynamical downscaling of the Seine basin climate for hydro-meteorological studies. International Journal of Climatology 27:1643-1655.
Themessl, M. J., A. Gobiet, and G. Heinrich. 2011. Empirical-statistical downscaling and error correction of regional climate models and its impact on the climate change signal. Climatic Change 112:449-468.
Gudmundsson, L., J. B. Bremnes, J. E. Haugen, and T. Engen-Skaugen. 2012. Technical Note: Downscaling RCM precipitation to the station scale using statistical transformations - a comparison of methods. Hydrology and Earth System Sciences 16:3383-3390.
Tohver, I. M., A. F. Hamlet, and S.-Y. Lee. 2014. Impacts of 21st-Century Climate Change on Hydrologic Extremes in the Pacific Northwest Region of North America. Journal of the American Water Resources Association 50:1461-1476.
Based on code from doQmapQUANT
v1.0.4 (Gudmundsson et al.
2012), but with additional methods and more granular control. See details.
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