Comments on: Long Instrumental Series

By: Hans Erren

Hans Erren — Tue, 12 Feb 2008 23:40:13 +0000

as requested in post 85 unthreaded #31

Armagh, CET and De Bilt have inhomogeneities in the early part.

http://www.metoffice.gov.uk/research/hadleycentre/CR_data/Daily/HadCET_act.txt
http://badc.nerc.ac.uk/data/armagh/445.pdf

By: Hans Erren

Hans Erren — Sun, 14 Aug 2005 08:23:07 +0000

I am still puzzled what the source of the “De Bilt”data in GHCN is.
I know of two sources in the literature:
1) Labrijn, A., 1945, Het klimaat van Nederland gedurende de laatste twee en een halve eeuw., KNMI mededeelingen en verhandelingen 49. (L1945)

2) A van Engelen and Nellestijn, JW, 1996: Monthly, seasonal and annual means of air temperature in tenths of centigrades in De Bilt, Netherlands, 1706-1995. KNMI report from the Climatological Services Branch (vEN1996)

Both datasets don’t show the 1850 jump, vEN1996 found some clerical errors in L1945. However, only in the pre 1734 data acquired by Cruquius a substantial difference is visible between the two datasets. Also the 1950 inhomogeneity was corrected by vEN1996.

By: Hans Erren

Hans Erren — Sun, 07 Aug 2005 11:03:33 +0000

re #4:
After a webserver crash the new url for the Labrijn ‘De Bilt’ series is:
http://home.casema.nl/errenwijlens/co2/LABRIJN.xls

By: JBK

JBK — Fri, 27 May 2005 23:56:47 +0000

Interesting that the 1816 Tambora “year without summer” downspike is visible on the average graph and on most of the the individual plots.

By: Michael Mayson

Michael Mayson — Fri, 27 May 2005 11:17:27 +0000

Re #8 Pedant you may be – but you are also right! Damn!

By: John A

John A — Fri, 27 May 2005 11:09:18 +0000

Re: #7

A boring pedant writes: 1783 was in the 18th Century.

By: Michael Mayson

Michael Mayson — Fri, 27 May 2005 02:52:15 +0000

Steve, I wonder if the big downspike in the late 17th century was as a result of major volcanic activity in Iceland. See this article http://www.newscientist.com/channel/earth/mg18625002.400
“In Europe they called 1783 the Year of Awe”

By: Paul

Paul — Fri, 27 May 2005 01:49:11 +0000

I remember two experiments with amazing results from my career in experimental high energy physics. The first was the “split A2″. Many subatomic particles are evanescent, they live 10^-21 seconds or so, and their signature is a resonance bump that is a Lorzentian, something like a Gaussian but with longer tails. The A2 had the remarkable feature of a deep hole right at the peak, and it was a 5 sigma effect. No one could understand it because it violated quantum mechanics and probability. The second experiment was the apparent discovery of quarks by an experiment at Stanford. They were clearly seeing electric charges that were 1/3 and 2/3 the charge of an electron. Both experimental results turned out to be wrong and the result of cherrypicking data (and ruined a few careers). The moral is that you have to include all data unless you can show that your equipment blew up in the process and the data you took was bad. If the experiment was properly calibrated and running you have to include the results, even if that Nobel Prize disappears in the statistical averaging.

Unless there is an experimental reason to exclude the red series or a statistic that clearly isolates the red series from the others there is no reason to exclude them from the analysis. Just by eye, the autocorrelation function is probably going to be very similar for all the series, a sharp peak with a tail.

The best method to avoid fooling yourself in a case like this is to develop the algorithms using dummy data generated by, for example, a Monte Carlo. Once you are sure that the algorithms are correct, then use them on all the real data, once. That way you can’t do the natural thing and fool yourself with exciting results from an unrepresentative small subsample of your data.

By: Steve McIntyre

Steve McIntyre — Fri, 27 May 2005 00:42:30 +0000

Dave, In the CEng series, the biggest downspike was in the late 17th century. The CEng series goes back to 1659, but the MBH98 version trunctes prior to 1730. We pointed this out in MM03. They subsequently attributed this version to Jones and Bradley [1992], the well-known article on the LIA. The cold late 17th century portion is also deleted from this version – without notice. It’s a little strange when they then argue that there was no LIA. A couple of years ago on sci.environment, they argued that this truncation was the “right” thing to do because of changing homogeneity, but then what to do about tree ring records, which are much worse for homogeneity. Also the version starting in 1659 is used in Jones et al 1998 and Jones and Mann 2004. So it’s hard for the Hockey Team to figure out a consistent position. Regards, Steve

By: Hans Erren

Hans Erren — Thu, 26 May 2005 22:11:14 +0000

re #1 That’s a data artifact in the GHCN version: an updated version was already published in 1996
A van Engelen and Nellestijn, JW, 1996: Monthly, seasonal and annual means of air temperature in tenths of centigrades in De Bilt, Netherlands, 1706-1995. KNMI report from the Climatological Services Branch.
Data here:http://hanserren.cwhoutwijk.nl/co2/LABRIJN.xls