Home > holocene > Steig Siple dD: 11th – 20th Century with Lowess

Steig Siple dD: 11th – 20th Century with Lowess

2012 May 13

Steve McIntyre has a post about Steig’s Siple dD series in which he posts a chart of the 20th century to undermine Schmidt’s claim that there are exceptionally high values in late 20th Century. And, indeed, the 20th century appears to be relatively trendless when eyeballed on that chart. McIntyre included his code.

Just for fun, given our recent discussion on lowess smoothing, I thought I would take a quick peek at the whole series with a lowess smooth. See above chart.

# http://climateaudit.org/2012/05/12/steigs-hockey-stick/#comment-333342
# code is only slightly modified from McIntyre's original
loc="http://faculty.washington.edu/steig/sipledome/SipleDomeCores_AB.txt"
	download.file(loc,"temp")
	work=read.table("temp",skip=3,header=TRUE)
	names(work)=c("year","dD","O18")
	work[work==999999]=NA
	steig=work

   trim=function(x) window(x, start= min(time(x)[!is.na(x)]),end=max(time(x)[!is.na(x)]) )
	dD=trim(ts(rev(steig$dD),start=995))
	x=window(ts(scale(dD), start=tsp(dD)[1]),1000)

png(file="siple_dD_full_lowess.png",h=420,w=600)
	plot(x,ylab="SD Units" ,xlim=c(1000,2000),ylim=c(-3,3),col="dark gray")
	title("Siple dD: 11th-20th Century")
	abline(h=0,lty=3)
	lines(lowess(x,f=0.40),col="green", lwd=2)
	lines(lowess(x,f=0.15),col="blue", lwd=2)
	lines(lowess(x,f=0.20),col="red", lwd=2)
	legend("topleft", legend = c("lowess f: 0.40","lowess f: 0.20", "lowess f: 0.15"),
		bty="n",lty=1, xjust = 1, yjust = 1, col=c("green","red","blue"), cex=0.9,,lwd=1)
dev.off()
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