The following two Google maps show Taimyr and Yamal on consistent scales, together with Schweingruber sites in the area.
The Taimyr chronology in Briffa 2000, as you may recall, not only didn’t have HS, but had a notable divergence problem.
I’ve tried to accurately transcribe onto this location map the Naurzbaev 2002 sites (subfossil – white circles; living – three yellow icons), the Schweingruber sites (green). Briffa 2008 reported the addition of the Avam site (yellow labeled), about 400 km from the center of the Taimyr samples. They did not report the addition of the Schweingruber Balschaya Kamenka site relatively near Avam.
[This is what I've figure out so far. The precise network used in Briffa 2000 remains unreported. I can sort of guess by crosschecking the network in Esper 2002, obtained through quasi-litigation at Sciencemag, but there are some puzzles. Briffa 2008 contains no metadata as to which site any given core belongs to.]
There are some Schweingruber sites that seem far more obvious additions to Taimyr than Balschaya Kamenka: for example, the Schweingruber Kotuy River and Kotuykan River sites are slightly uphill from the Naurzbaev Kotuy River samples. The Schweingruber Novoja Rieka site seems to be almost co-located with a Naurzbaev location.
Why did Briffa go all the way to Balschaya Kamenka to add a Schweingruber site, while passing over the nearby sites? In the case of Yamal, where he also omitted a nearby site, Briffa said that they didn’t “simply” didn’t consider the nearby Khadyta River, Yamal site. Perhaps the same thing happened here.
Next here is a corresponding map for Yamal on precisely the same scale. Briffa’s online article made a bit of an issue of the fact that the Schweingruber Khadyta River, Yamal site was “slightly to the south” of the Porza and Yadaya sites – mentioning this not once but twice. However, Khadyta River is obviously far closer to the Porza and Yadaya sites than Avam or Balschaya are to Taimyr.
Polar Urals is also closer to Yamal than Avam is to Taimyr (I’ve got two slightly different latitudes for this site in my data collations – the present NCDC location has a latitude of 66 50N (but my collation of the Schweingruber locations once at NCDC but no longer there has a latitude of 67 50N). For present purposes, both locations are closer to Yamal than Avam is to Taimyr. Briffa said that he didn’t include Khadyta River in the Yamal RCS, because he “simply didn’t consider it”. He didn’t report on his deliberations regarding Polar Urals. Was it not included in the RCS because Briffa “simply didn’t consider it” or for some other reason?
These are elementary and obvious questions. Why are some sites included and some excluded? What are the scientific principles involved? Gavin Schmidt accused me of “randomly” picking a site off the internet, but that is not what I did. Given the precedent use of a Schweingruber site at Taimyr, I looked for the closest Schweingruber site to Yamal. In contrast, Briffa provided no guidance as to the basis for including one Schweingruber site rather than another. Did Briffa “randomly” pick Schweingruber sites to add – right now, we have no way of knowing?
Advocates at realclimate and elsewhere urge us to defer to Briffa’s choices. If Briffa’s articles are to be viewed as a branch of prophetic or oracular literature, then followers are, of course, entitled to defer to his choices.
However, if Briffa’s articles are to be considered as scientific articles, then the selection criteria need to be clearly stated and it should be possible to verify the choices. At present, I am not saying that there were no such rational criteria, only that the articles do not say what they were and, thus far, I have been unable to deduce what the criteria were.