My comment arises from exercises with drill core in rock, not from hands-on with ice cores, and from having once owned a lab where various instruments were used, including isotope counters of several types. That is the basis for my general statement that few routine analytical instruments will return accuracy better than 3 significant figures. Ratio this and the errors compound.

On this blog there is a lot of discussion about “adjustments” to climate data. You will know of course that prior to that stage, there are often laboratory and other “adjustments” made to the data being adjusted for climate factors. There is no instrinsic reason why the many errors in climate records needing adjustment do not likewise happen in the pre-climate adjustments. Smoothing temp data with sensors of different response times comes to mind. When climatology studies address land albedo and need multi-element soil analysis, the ICP and XRF type instruments that could well be used have rather similar multivariate, sometimes non-linear, regression matrices applied before the data even reach the climatologists. Is this another whole field of investigation, or do we take it that analsyses are free of subjective correctional inputs?

There should be readers of this blog who can compare left to right side oxygen isotope results from ice cores. It’s a fundamental part of the quality control process, if done properly.

Do you want to go to jail?

#url=”d:/climate/data/FISHER/core-interEOF”
url=”http://data.climateaudit.org/data/ice/fisher”
loc=file.path(url,”DELNORM6.CWG”)
fred=readLines(loc)
write.table(fred[4:148],”temp.dat”,quote=FALSE,row.names=FALSE,col.names=FALSE)
test=scan(“temp.dat”)
delnorm6=ts(rev(test),start=553)

w.

ANNUAL DELTAS USING MASK FILE L74-12.CRT & DATA FILE CT74-12.CRT
CRETE 1974 DELTA-18. 1ST YR IS 1973AD . LAMBDA=28.7 CM/YR ICE
922 1 1

and I have confirmed that the “922″ is the actual years of data in the dataset.

This, of course, means that the first year in the dataset is 1052 AD, while the DELNORM dataset claims that it covers the period from 1062 to 553 AD.

I looked up the “MASK FILE” listed above, L74-12.CRT, and the “DATA FILE”, CT74-12.CRT, in the ice core documentation. They are listed as:

L74-12.CRT
CRETE 1974 CORE DELTA-18. ACCUMULATION . STARTS 1974-553 AD. LAMBDA=28.7 CM/ ICE EQUIV. BASED ON DETAILED DEL CURVE. CM/YR ICE. (CRETE74/12ACC) FIRST VALUE IS WINTER TO SUMMER 1975 (ROUGHLY 1/2 YEAR)

and

CT74-12 .CRT
CRETE 1974 DELTA-18. 12/ YR . STARTS 1974-553 AD . LAMBDA=28.7 CM/YR ICE THE BIG ONE EH. %. 2.391666 CM AVES . (CRETE74/12) DRILLED IN SPRING OF 1975. APPROXIMATELY 12 SAMPLES PER YEAR, BUT VARIABLE. 2ND VALUE IS WINTER 74/75.

Both of these go back to 553 AD.

Stranger and stranger … all clarifications gladly accepted.

w.

27, that’s a good explanation. Very roughly like CT scanning, where you’re able to improve S/N ration by having multiple angles on the same thing.

The same thing is done in radar to smooth the fluctuation of radar cross section (i.e. how “big” the target looks) which most targets exhibit.

Mark