I’ve been trying for nearly a year to get a digital version of the Tornetrask reconstruction of Grudd (2008), also referred to in his thesis.
Last week, Hakan Grudd sent me a digital version of the MXD series – hooray! Previously I’ve previewed this new version using clips from the articles or thesis e.g here.
Because Tornetrask is used in every recon, I needed this new version to test the overall impact of the newer versions of key series. In the first figure below, I’ve plotted the three successive versions of Tornetrask – top, from Briffa et al 1992, the scene of what Per referred to as a “gobsmacking” adjustment, discussed here; middle from Briffa 2000, a version used in some later studies (though Juckes et al 2007 used the 1992 version on the pretext that “scientific” procedure mandated the use of older data) ; bottom – from Grudd 2008.
The three versions are overlaid in a smooth version in the 4th panel showing that the Grudd version has an elevated MWP relative to the modern period, that is not present in the Briffa versions.
Next here is a figure showing the differences between the two earlier versions and the current Grudd 2008 version. Some people might even notice a little HS-ness in the difference between the two series.
In one of my earliest posts (before the Grudd version became available), I had noted that Briffa had “adjusted” his reconstruction and, as it happens, the amount of his adjustment is more or less equivalent to the difference between the Briffa 1992 version (used in many studies) and the present version. Thus some portion of the reconstructions using the Briffa 1992 version are an artifact.
Here is the diagram that I presented in the earlier post.
Figure 3. Top panel: Tornetrask. RW (red) and MXD (black) chronologies. Second panel (compare to CD92 Figure 7): Black – residuals after regressing MXD against RW based on 500-1750; red line – “trend” of residuals after 1750; red – “adjusted” residuals. Third panel – “adjusted” MXD chronology after adding back “adjusted” residuals. Bottom panel – MXD chronologies with 1902-1980 zero (additional 25-year smooth). Black – unadjusted; red – “adjusted”. Note the change in 20th century relative to other periods.
In a recent post, I discussed Briffa et al 2008 (hot off the press), which included Tornetrask, mixed in some proportion with Finnish Lapland. As noted in my discussion of this post, no data was archived. I have just heard back from the journal and will profile this separately.
Here’s the figure from Briffa et al 2008. Squinting at it, it looks more like one of the earlier versions than the Grudd 2008 version. This could reflect the impact of blending Finnish Lapland data or it could be the use of an older Briffa version. Time will tell.
Original Caption: Briffa et al 2007 Figure 3. Regional curve standardized (RCS) chronologies (thin lines) and smoothed chronologies, the sum of the first three components of singular spectrum analysis of each RCS chronology (thick lines), for the regions: (a) Fennoscandia, … The grey shading represents the changing number of samples that go to make up the chronology through time.