Low-level interpolation functions

Low-level functions to interpolate meteorology (one day) on a set of points.

interpolation_dewtemperature(Xp, Yp, Zp, X, Y, Z, T, 
                             iniRp = 140000, alpha = 3.0, N = 30, 
                             iterations = 3, debug = FALSE)
interpolation_temperature(Xp, Yp, Zp, X, Y, Z, T, 
                          iniRp = 140000, alpha = 3.0, N = 30, 
                          iterations = 3, debug = FALSE)
interpolation_precipitation(Xp, Yp, Zp, X, Y, Z, P, Psmooth,
                            iniRp = 140000, alpha_event = 6.25, alpha_amount = 6.25,
                            N_event = 20, N_amount = 20, iterations = 3, popcrit = 0.5, 
                            fmax = 0.95, debug = FALSE)
interpolation_wind(Xp, Yp, WS, WD, X, Y,
                   iniRp = 140000, alpha = 2.0, N = 1, iterations = 3,
                   directionsAvailable = TRUE)

Arguments

Xp, Yp, Zp

Spatial coordinates and elevation (Zp; in m.a.s.l) of target points.

X, Y, Z

Spatial coordinates and elevation (Zp; in m.a.s.l) of reference locations (e.g. meteorological stations).

T

Temperature (e.g., minimum, maximum or dew temperature) at the reference locations (in degrees).

P

Precipitation at the reference locations (in mm).

Psmooth

Temporally-smoothed precipitation at the reference locations (in mm).

WS, WD

Wind speed (in m/s) and wind direction (in degrees from north clock-wise) at the reference locations.

iniRp

Initial truncation radius.

iterations

Number of station density iterations.

debug

Boolean flag to show extra console output.

alpha, alpha_amount, alpha_event

Gaussian shape parameter.

N, N_event, N_amount

Average number of stations with non-zero weights.

popcrit

Critical precipitation occurrence parameter.

fmax

Maximum value for precipitation regression extrapolations (0.6 equals to a maximum of 4 times extrapolation).

directionsAvailable

A flag to indicate that wind directions are available (i.e. non-missing) at the reference locations.

Value

All functions return a vector with interpolated values for the target points.

References

Thornton, P.E., Running, S.W., White, M. A., 1997. Generating surfaces of daily meteorological variables over large regions of complex terrain. J. Hydrol. 190, 214–251. doi:10.1016/S0022-1694(96)03128-9.

De Caceres M, Martin-StPaul N, Turco M, Cabon A, Granda V (2018) Estimating daily meteorological data and downscaling climate models over landscapes. Environmental Modelling and Software 108: 186-196.

Author

Miquel De Cáceres Ainsa, CREAF

Examples

data("exampleinterpolationdata")
mxt100 = exampleinterpolationdata@MaxTemperature[,100]
Psmooth100 = exampleinterpolationdata@SmoothedPrecipitation[,100]
P100 = exampleinterpolationdata@Precipitation[,100]
mismxt = is.na(mxt100)
misP = is.na(P100)
Z = exampleinterpolationdata@elevation
X = exampleinterpolationdata@coords[,1]
Y = exampleinterpolationdata@coords[,2]
Zpv = seq(0,1000, by=100)
xp = 360000
yp = 4640000
xpv = rep(xp, 11)
ypv = rep(yp, 11)

interpolation_temperature(xpv, ypv, Zpv, 
                          X[!mismxt], Y[!mismxt], Z[!mismxt], 
                          mxt100[!mismxt])
#>  [1] 22.40368 21.27964 20.15560 19.03156 17.90752 16.78348 15.65944 14.53540
#>  [9] 13.41136 12.28732 11.16328
interpolation_precipitation(xpv, ypv, Zpv, 
                           X[!misP], Y[!misP], Z[!misP], 
                           P100[!misP], Psmooth100[!misP])
#>  [1] 1.9533075 1.7282254 1.5350844 1.3674476 1.2205184 1.0906441 0.9749912
#>  [8] 0.8713261 0.7778630 0.6931565 0.6160236