“These chronologies were detrended using so-called standard techniques (either negative exponential or regression functions of negative or zero slope).”

The handling of each of the 15 sites is quite different. Data is archived for some of the sites (N Scandinavia, Kyrgyzstan, one Mongolia site, Nepal, Idaho, B.C., Yukon North, Wrangells), but is not archived for others (Alps, Tatra, W Siberia, one Mongolia, Tien Shan, Colorado, Yulon South, N Quebec). Rob’s descriptions are relatively good by dendro standards.

In some cases, Rob re-calculated chronologies; in other cases, he did not. For example, he didn’t re-calculate the Salzer and Kipfmueller chronology. In Appendix A7 (Kyrgyz) he said:

Chronologies were computed using standard techniques.

I think that the paper makes it sound like ITRDB/Schweingruber used standard techniques; in his email to me, Rob said that:

As I clearly state in the paper, I use the same standard approach to detrending for all sites where I had access to raw data.

The method is described for the Scandinavia composite. I did not have to repeat it again. i.e. standard methods.!!

So readers can be assured that Rob’s email said that these methods were used for Kyrgyz as well. I more or less know what Rob’s doing and I can get results that look sort of like his, but so far I can’t replicate his results. His Sarejmek data set excludes 4 cores that were included in the ITRDB data set, but differences between his chronology and the ITRDB chronology cannot be attributed to this difference and the Tschongkyz datasets match. As to methodology, I’d like to see methodologies that say that he used COFECHA Option 2 (or whatever) – that’s all that I’m saying here. But I’ll clarify the point in the post for future readers.

As stated in Appendix A3 for Northern Scandinavia

These chronologies were detrended using so-called standard techniques (either negative exponential or regression functions of negative or zero slope).

This approach was used for all data I had raw data for.
Very easy to replciate if you took the trouble to do so.

Rob

This doesn;t entirely resolve things however, as I still get noticeable differences. I’ll take a more detailed look at Rob’s chronologies and try to resolve these. I notice that his russ152w measurement data set excludes 4 trees relative to the russ152w.rwl data set at ITRDB – I’m not quite sure why or what impact this has.

In addition, Rob has not commented on the flipping of the russ164w series in the course of the linear regression. If there is a relationship between temperature and ring widths, then there should be a consistent relationship between the coefficients. This sort of sign flipping is overfitting pure and simple and creates a false fit between the chronologies and the temperature data, which, in this case, enhances the trend.

As a rule, if I can get get my hands on raw data, I will process my own chronology. That was not always possible for the JGR paper. As for published reconstruction (e.g. Salzer and Kipfmueller) I would used the archived reconstruction.

Standard methods – as you know fine well – are the use of negative exponential functions or linear regression functions of negative or zero slope.

and yes – my paper was the ultimate cherry-pick and it was a joy to try and make cherry pie. I usually am only good at cooking curries.
The paper was trying to address divergence issues at large scales and I needed to work with proxies that showed no divergence at the local scale.

Rob

A search through the ITRDB, found surprisingly few temperature sensitive TR data sets that came up to at least 1995. Kyrgyzstan was one region where such chronologies were found (sampled and measured by the Swiss Federal Institute for Forest, Snow and Landscape Research). In this region, both RW and MXD data were obtained from two spruce (Picea shrenkiana) sites Sarejmek (ITRDB code: RUSS152, 41.36N 75.09E) and Tschongkys (RUSS164 42.11N 78.11E).

Isn’t this the same kind of cherry-picking Jacoby did with the cedar data, except on a bigger scale? See “A few good series” threads: http://www.climateaudit.org/?p=29, http://www.climateaudit.org/?p=570. Out of 1000 series unrelated to temperature, we would expect to be able to find about 10 that are individually “highly significant” at the 1% level.

Or is this your point?

Having said that, I did my own chronology calculation using a Jacoby style and got a very different looking result, one without the high early values – more like what must underpin the Wilson recon. So the measurement data can support a different chronology than the one actually archived.

This poses a couple of questions – if there is a defect in the archived Schweingruber and ITRDB chronologies, what caused the problem, how prevalent is the problem and why did QC procedures fail to pick it up?

Second, who actually calculated the chronology version used by Wilson (leaving aside the question of whether the recalculation has merit relative to the ITRDB version)? Why was this particular chronology re-calculated, while the Salzer and Kipfmueller chronology wasn’t? When they noticed the problem with the ITRDB chronologies, did they notify ITRDB? If not, why not?