mixFields {clim.pact}R Documentation

mixFields

Description

Mix fields by combining two different gridded sets of observation. Observations/data for representing values at n different locations at a given time (t) can be described in terms of a vector

x(t)=[x_1, x_2, ... x_n].

Two different sets of observations can be represented by two vectors y and z of lengths n and m respectively. In mix.fields, the information in these two data sets are combined combining the two vectors:

x(t)=[y(t), z(t)]= [y_1, y_2, ... y_n, z_1, z_2, ... z_m].

The length of the final vector of the mixed field is the sum of the lengths of the two respective vectors. The two data sets do not have to be on the same grid.

reference: Bretherton et al. (1992) "An Intercomparison of Methods for finding Coupled Patterns in Climate Data", J. Climate, vol 5, 541-560.

The output from mixFields can be used in EOF to compute mixed-common EOFs which subsecuently can be used as predictors in DS in order to downscale climate scenarios (Benestad et al. (2002), "Empirically downscaled temperature scenarios for Svalbard", Atm. Sci. Lett., doi.10.1006/asle.2002.0051).

The functions combineFields and combineEOFs bundle together fields of different parameters, and allows downscaling of multiple variables, but without performing a mixed-EOF analysis. Thus, allows ESD with a multiple regression analysis involving both e.g. SLP and T(2m) as input variables as in traditional multiple regression:

y(t)=a0 + a1 x(t) + a2 + z(t) + ...

Usage

mixFields(field.1,field.2,mon=NULL,interval=NULL)
combineFields(field.1,field.2)
combineEOFs(eof.1,eof.2)

Arguments

field.1 A 'field.object'.
field.2 A 'field.object'.
eof.1 An 'EOF.object'.
eof.2 An 'EOF.object'.
mon Calendar month to extract.
interval Time interval to extract.

Value

A 'field.object'.

Author(s)

R.E. Benestad

Examples

## Not run: 
library(clim.pact)
x.1 <- retrieve.nc("/home/kareb/data/ncep/ncep_t2m.nc",
                   x.rng=c(-60,40),y.rng=c(50,75))
x.2 <- retrieve.nc("/home/kareb/data/ncep/ncep_slp.nc",
                   x.rng=c(-60,40),y.rng=c(50,75))
print(x.1$v.name)

print("Read GCM predictor data.")
X.1 <- retrieve.nc("data/mpi-gsdio_t2m.nc",
                   x.rng=c(-60,40),y.rng=c(50,75))
X.2 <- retrieve.nc("data/mpi-gsdio_slp.nc",
                   x.rng=c(-60,40),y.rng=c(50,75))
print(X.1$v.name)
print("Cat fields.")
xX.1 <- catFields(x.1,X.1,interval.1=c(1958,1998),interval.2=c(1958,2050))
xX.2 <- catFields(x.2,X.2,interval.1=c(1958,1998),interval.2=c(1958,2050))
xX <- mixFields(xX.1,xX.2,mon=1,
                 interval=c(1900,2050))
print("EOF")
eof.c <- eof(xX.1,mon=1)
eof.mc <- eof(xX,mon=1)

## End(Not run)

[Package clim.pact version 2.2-15 Index]