wcs {sowas}R Documentation

Wavelet Sample Cross Spectrum

Description

This funtion estimates the wavelet cross spectrum of two time series objects with the Morlet wavelet.

Usage

wcs(ts1, ts2, s0 = 1, noctave = 5, nvoice = 10, w0 = 2 *
  pi, sw = 0, tw = 0, swabs = 0, markt = -999, marks =
  -999, logscale = FALSE, phase = TRUE, plot = TRUE,
  units = "", device = "screen", file = "wcsp", split =
  FALSE, color = TRUE, pwidth = 10, pheight = 7, labsc =
  1, labtext = "")

Arguments

ts1 first time series object to be transformed
ts2 second time series object to be transformed
s0 lowest calculated scale in units of the time series
noctave number of octaves
nvoice number of voices per octave
w0 time/frequency resolution omega0
sw length of smoothing window in scale direction is 2*sw*nvoice+1
tw length of smoothing window in time direction is 2*s*tw+1
swabs length of smoothing window in scale direction at scale s is 2*swabs+1
markt vector of times to be marked by vertical dotted lines; when set to -999 (default), no lines are plotted.
marks vector of scales to be marked by horizontal dotted lines; when set to -999 (default), no lines are plotted.
logscale when TRUE, the contours are plotted in logarithmic scale
phase TRUE when phase calculation desired
plot TRUE when graphical output desired
units character string giving units of the data sets. Default: ""
device "screen" or "ps"
file character string giving filename of graphical output without extension
split when TRUE, modulus and phase are splitted into two files; default: FALSE
color TRUE (default): color plot, FALSE: gray scale
pwidth width of plot in cm
pheight height of plot in cm
labsc scale of labels, default: 1, for two-column manuscripts: 1.5, for presentations: >2
labtext puts a label in upper left corner of the plot

Details

WARNING! Better do not use this function because it is in general easily misinterpreted! A peak in the wavelet cross sample spectrum appears in the three cases, that either the first processes exhibits a peak, or the second process or both. But it does not tell, what case is observed. So in general, a peak in the wavelet cross sample spectrum does not imply that the two underlying processes are related in any way. The function returns an object of type "wt", that might be directly plotted by the plot function.

Value

modulus matrix of modulus of wavelet sample cross spectrum of dimension [length(intersection of ts1 and ts2)]x[nvoice*noctave+1]
phase matrix of phase of wavelet sample cross spectrum, same dimension as modulus
s0 lowest calculated scale in units of the time series
noctave number of octaves
nvoice number of voices per octave
w0 time/frequency resolution omega0
time vector of times of length(intersection of ts1 and ts2)
scales vector of scales of length nvoice*noctave+1
critval not used
at not used
kernel not used

Note

Author(s)

D. Maraun

References

D. Maraun and J. Kurths, Nonlin. Proc. Geophys. 11: 505-514, 2004

See Also

cwt.ts, wsp, wco

Examples

##
data(nao)
data(nino3)

# wcs mimics peaks of coherent power, where in reality are non to be
# found, as wco shows (see FAQs on my homepage)
# Thus, never use wcs! :-)
wcsp.nao.nino3 <- wcs(nao,nino3,s0=0.5,noctave=5,nvoice=10)
wcoh.nao.nino3 <- wco(nao,nino3,s0=0.5,noctave=5,nvoice=10,sw=0.5,arealsiglevel=0)
[Package sowas version 0.93 Index]