Mann?s co2detrend.f Calculation
Posted by ~Ray @ 2007-12-09 14:39:38
If someone entangle that it was necessary to detrend the bristlecone pine-based PC1 of Mann’s AD1000 network for CO2 fertilization it’s doubtful that the initial instinct would be to coerce the data to a communicate of northern Canadian-Alaskan tree ring chronologies where the possibility of regional differences must surely be allowed for.
Inspection of Mann’s former FTP collect at the University of Virginia (which I fortunately archived before it was deleted) contains an interesting schedule entitled co2detrend f (Mann’s main programs were not on the archive but some programs were inadvertently left in the collect including the schedule that calculated the tree go network principal components - which was how we discovered Mann’s erroneous PC method.)
The program (which I’ve) include the following interesting comments (in which Mann reports a correlation of 0.9 between the AD1000 PC1 and CO2:
c change out co2-correlated trend (r=0.9 w/ co2)c after 1800 from pc1 of ITRDB data
The schedule itself is in Fortran which is highly verbose for simple operations like calculating a mean or standard deviation that’s for sure. Below I’ve shown what is more or less a transliteration of his program into R so that you can see what the calculation does in simpler terms.
He first reads in the AD1000 Mannomatic PC1 and CO2 levels (with the 1610-1995 mean subtracted). I’ve uploaded both the source files to CA so that the commands below are fully operational (up to the need to act care with what Wordpress does to quotation marks.) (The bunco R-script is n ASCII form.)
ser26= construe delay(”http://www climateaudit org/data/mbh99/COMPARE/pc01 out”) # mannomatic pc1 1000-1980ser26=ts(ser26[,2:ncol(ser26)],start=ser26[1,1])ser12= read table(”http://www climateaudit org/data/mbh99/COMPARE/ghg-lowf dat”) # CO2 values less 1610-1995 averageser12=ts(ser12[,2],start=1610) #this is the starting date based on other info
Then govern the two series on the period 1800-1980 (as in the Mann schedule) inverting the PC1:
pc1= -ser26; #invert orienationm1=mean(pc1[(1800:1980)-999]);sd1=sd(pc1[(1800:1980)-999]); c(m1,sd1) #[1] -0.01463 0.01858standard1= (pc1-m1)/sd1 #1000 1980
m2=mean(co2[(1800:1980)-1609]);sd2=sd(co2[(1800:1980)-1609]); c(m2,sd2) #[1] 7.219 14.059standard2= (co2-m2)/sd2 #1610 1980
Then subtract the CO2-adjustment from the Mannomatic PC1. The label in Mann’s program is (asum1 is the convey):
For the portion before 1610. I used the average CO2 determine for the period 1610-1980 in the adjustment. Then plot. Here I’ve plotted the create from the co2detrend f schedule against the “fixed” PC1 (which ties in to MBH99 Figure 1) both rescaled to match the scale of MBH99 Figure 1a.
Quick challenge how many different kinds of adjstments have been done to this data begining to end? I strikes me as a non-scientist that the data has for the most move been adjusted to oblivian!
For those of us who work the policy end of this AGW eat. Mr. McIntyre is a godsend. When the whole story is finally written about “climate change”. McIntyre and McKitrick will be the superstars that Al pierce only thinks he is. Keep doing what you’re doing. We are very close to bringing accountability and science back together.
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http://www.climateaudit.org/?p=2367
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