chron function

Build Mean Value Chronology

This function builds a mean value chronology, typically from a data.frame of detrended ring widths as produced by detrend. UTF-8

chron(x, biweight = TRUE, prewhiten = FALSE, ...)

Arguments

• x: a data.frame of (usually detrended) ring widths with rownames(x) containing years and colnames(x)

  containing each series ID such as produced by read.rwl

• biweight: logical flag. If TRUE then a robust mean is calculated using tbrm.

• prewhiten: logical flag. If TRUE each series is whitened using ar prior to averaging.

• ...: Arguments passed to ar when prewhiten is TRUE. For example, use aic

  and order.max to control the order of the AR model.

Details

This either averages the rows of the data.frame using a mean or a robust mean (the so-called standard chronology) or can do so from the residuals of an AR process (the residual chronology).

Note that the residual chronology in this function will return different values than the residual chronology from chron.ars which uses a slightly different method for determining AR order.

Returns

An object of of class crn and data.frame with the standard chronology, residual chronology (if prewhitening was performed), and the sample depth. The years are stored as row numbers.

References

Cook, E. R. and Kairiukstis, L. A., editors (1990) Methods of Dendrochronology: Applications in the Environmental Sciences. Springer. ISBN-13 : 978-0-7923-0586-6.

Fritts, H. C. (2001) Tree Rings and Climate. Blackburn. ISBN-13 : 978-1-930665-39-2.

Author(s)

Andy Bunn. Patched and improved by Mikko Korpela.

See Also

read.rwl, detrend, ar, crn.plot

Examples

library(graphics)
library(utils)
data(ca533)
ca533.rwi <- detrend(rwl = ca533, method = "ModNegExp")
ca533.crn <- chron(ca533.rwi)
plot(ca533.crn,xlab="Year",ylab="RWI")
## With residual chron
ca533.crn2 <- chron(ca533.rwi, prewhiten = TRUE)
plot(ca533.crn2,xlab="Year",ylab="RWI")