The Yamal Substitution

The Polar Urals temperature reconstruction (Briffa et al, 1995) has been a mainstay of multiproxy studies. More data was collected at this site in 1998 (russ176), but in the two new studies (Osborn and Briffa, 2006; D’Arrigo et al., 2006), they relate their site selection to the Polar Urals, but substitute the Yamal RCS series (oddly, D’Arrigo et al. use the Polar Urals data for the spline standardization (STD)). What accounts for the Yamal substitution?

Also see here here here here.

Here’s a figure comparing the Yamal version (as archived at Briffa’s website) – the plot of which looks a little different than the plot in D’Arrigo et al. 2006 for reasons that I don’t yet understand – and an RCS chronology that I calculated for the combined russ021w and russ176w datasets.

There is no explanation in either text for the Yamal substitution. Rob Wilson has sent me an explanation offline, which he can post up if he wants, but doesn’t make any sense to me. However, one rather unsavory explanation for the Yamal substitution jumps out merely by looking at the series. When you’re dealing with small datasets – e.g. the 6 series average shown in DWJ Figure 7 or robustness to 2-3 series being excluded, these little substitutions have a knock-on effect on both averages and exceedances.

Top – Yamal; bottom – RCS for Polar Urals – combined russ021 and russ176. Both scaled.


  1. per
    Posted Feb 12, 2006 at 5:27 PM | Permalink

    the issue of proxy selection is such an important one. It makes a real compelling case for having an expert statistician on the NAS panel.

  2. Steve Sadlov
    Posted Feb 13, 2006 at 10:29 AM | Permalink

    Did someone get a certain email forwarded to them that called for a crusade to eliminate the MWP? Looking first at the lower plot then the upper one, that sodden thought did occur to me. “Oh, that MWP thingy? Pay it no mind, it was just noise …..”

  3. kim
    Posted Feb 15, 2006 at 7:07 AM | Permalink

    Well there’s another chaotic system from which there ought to be multiproxy statiticians who could understand this problem, and that is market economics. Or is that all too grubby?

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  1. […] members dropped Polar Urals altogether and substituted Briffa’s Yamal series in its place. PS: The exception to this pattern was Esper et al (Science) 2002, which used the combined Polar […]

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