I’ve been looking recently at some issues in the post-1820 proxy data and re-noticed some things that I’d seen before but lacked my present context.
Most of you are familiar with the CRU temperature series since 1850. Of course, there are instrumental series that go before that. MBH98 used 12 long instrumental series. There are 14 such series archived at the UVA FTP website (in standard deviation units). Here is a graph showing the average of these series up to 1980 (as archived.
Figure 1. Average of MBH98 long instrumental series up to 1980.
Below I show the individual times series.
Obviously, the long instrumental temperature series do not show the iconic hockey stick shape. This is such an obvious graph to plot that one wonders why it wasn’t shown in MBH98 itself. Here is a plot of the underlying series, which are almost entirely European in origin. The two series shown in red were excluded in MBH98 for unstated reasons – one of them is the well-known De Bilt series (beloved of Hans Erren). Mann et al. have never reported the source of the instrumental data. It was incorrectly cited in MBH98 as Jones and Bradley . The Corrigendum only said "NOAA". Nature refused to require more specificity.
I’ve tracked most of the series as being exact linear transformations of data versions in ndp-041, but some are still puzzles.
Figure 2: Long instrumental temperature series at MBH98 FTP site (presumably standard deviation units).
Proposed identifications columnwise top to bottom: Minneapolis, Paris, Geneva, Kremsmuenster, Wien, De Bilt, Wroclaw, Warszawa, Stockholm, St. Peterburg, Bergen, Trondheim, Arkhangel, Central England. Red – archived but not used. Minneapolis, Paris, Stockholm, St. Peterburg, Bergen, Trondheim, Arkhangel have correlation of 1 to ndp-041 version; C England version is identical to JJA version at C1500 archive [check]. Wien and Wroclaw have correlations >0.975; Geneva and Kremsmuenster >0.8. I was looking at these series in connection with the attenuation of variance in earlier portions of the MBH98 reconstruction. This does not occur in the long instrumental series – I’ll show which ones are affected on another day.
Another curiosity: remember how Briffa complained that the proxies were not keeping up with temperature post-1960? I showed some graphs showing that this was a widespread problem in both MXD and ring width series. Here we have the opposite situation: in this dataset, the "proxies" are outstripping the instrumental series. So we have (at least) two interesting problems here:
1) why is the trend in the long instrumental series so different from the temperature PC1 and the CRU average?
2) why are MBH98 tree ring data outstripping instrumental temperatures (e.g. bristlecones growth), when tree rings are not doing so on an overall basis?
To answer the first question, one needs to do a detailed site-by-site analysis of the CRU dataset. This is prevented by Phil Jones’ refusal to let potential critics look at the underlying station data. (Look at the Top 15 Reasons for withholding data – he’s the guy with "25 years invested in this work".) Given that his work has been funded by the U.S. DOE, I doubt that he will be able to stonewall forever – there’s more than one way to skin a cat. The second question leads to interesting issues of cherrypicking proxy series. I’m trying to work up a statistical method of demonstrating cherrypicking and have some thoughts on how to do this, but they are still preliminary.