“MXD Climate” brings up:
http://www.climateaudit.org/?p=150
Figure 1 below shows the following Tornetrask maximum density (MXD) chronologies

Searching on “maximum density (MXD) chronologies” will bring up numerous references on the topic.

Steve: It’s not that the archive was empty. What I said was that it didn’t contain the MXD data. This directory contained a placeholder saying to contact Tim Osborn, which I did, but he refused to provide the data. As I mentioned above, I tried again recently using UK FOI legislation and had some success.

Classic

http://noconsensus.wordpress.com/2008/10/05/mxd-tree-removal-service-choppin-wood-off-a-hockey-stick/

I separately searched “Briffa” and “Osborn” in “Global and Planetary Change,” and only one paper turned up: K. R. Briffa, T. J. Osborn, and F. H. Schweingruber (2004) “Large-scale temperature inferences from tree rings: a review” Global and Planetary Change 40(1-2), 11-26, now BOS04. The 2004 date is reasonable for a “submitted” comment in Rutherford, 2005, because R05 was itself submitted only in September 2003. BOS04 is thus likely to be “OSB.”

BOS04 (OSB) is a review article with no Methods Section, no equations or mathematical descriptions of any kind, and no supplemental information. That is, it is not the sort of article where one expects to find a complete, or even a useful, methodological description.

The only relevant passage I found in BOS04 regarding grid-box calibration was in the legend to Figure 8: “Average temperature over land areas north of 20°N, as observed (black) and reconstructed by a simple linear regression recalibration of published series by [Jones et al., 1998] in red; [Mann et al., 1999] in purple; [Briffa and Osborn, 1999] in green; [Briffa et al., 2001] in blue; and [Esper et al., 2002] in pink. The series used from [Mann et al., 1999. M.E. Mann, R.S. Bradley and M.K. Hughes, Northern Hemisphere temperatures during the past millennium: inferences, uncertainties and limitations. Geophysical Research Letters 26 (1999), pp. 759–762. Mann et al., 1999] was an average of land grid boxes north of 20°N from their spatially resolved reconstructions. Each series was recalibrated over 1881–1960 against, (a) annual-mean temperature and (b) April–September mean temperature. Note the effect on the temperature magnitudes in the two sets of series caused by calibrating the same data against these alternative predictands.”

This isn’t a particularly detailed description of what was done.

Also, in Figure 6: “Fig. 6. (a) Instrumental temperatures (red) and tree-ring density reconstructions of temperature (black) averaged over all land grid boxes north of 50°N, smoothed with a 5-year low-pass filter.”

I found nothing in BOS04 that described any infilling of missing data. Yet another small mystery, given the statement in R05 that, “OSB add this missing low-frequency variability to each grid box in a region.”

Steve: Thanks for this. I missed that definition – I’d read the article and, as you say, it doesn’t describe the method. I’ve edited the text to clarify this.