Tuesday, June 29, 2010

Ari Jokimäki Looks at the Tiljander Proxies

This post is a placeholder (29 June 2010). The immediate intent is to provide a link to two sites. This post was written on 29 June 2010; corrections and minor additions made on 7 July 2010 are in italics. The objective is to provide some data and links to accompany recent posts by Ari Jokimäki and Arthur Smith.

First, Ari Jokimäki's new analysis of the Tljander proxies, particularly XRD, X-Ray Density. His post at AGW Observer is Tiljander.

Second, here is a link to the Excel file Kort-gridbox-CRUtemv3.xls, which contains monthly and annual CRUtemv3 CRUTEM3v temperature anomaly records for the 5 degree by 5 degree gridbox that includes Lake Korttajarvi. It is downloadable from Bitbucket by clicking on the filename.


Note that the file contains two graphs of temperature anomaly vs. time for that gridcell.  Here is the first:  annual aveage temperature anomaly vs. time, along with the line generated by Excel's linear regression tool.



The second graph adds the Tiljander X-Ray Density (XRD) proxy, using an 11-year rolling average. Note that the XRD proxy is plotted in its "upside-down" orientation. In other words, by the assignment of Tiljander et al. given in their 2003 Boreas article, "colder" is towards the top of the graph, while "warmer" is towards the bottom.

However, climactic influences on the XRD proxy are of limited relevance with respect to these 19th and 20th Century values, according to Tiljander et al.  The XRD record during this time is dominated by local non-climate-related contaminating factors.  For details, refer to the "Jarvykortta River" post.



The screening, validation, and calibration exercises in Mann08 relied on two instrumental surface-air temperature data sets for 1850-2006, maintained by the University of East Anglia's Climatic Research Unit instrumental surface-air temperature data from 1850 to 2006. CRU's records are archived at this page. "CRUTEM3v" estimates land temperature anomalies; "HadCRUT3v" estimates them for land and ocean combined. "v" refers to the adjustment by CRU of the anomaly values for variance.

The 5-degree by 5-degree gridbox that includes the Lake Korttajarvi bore hole site encompasses 60N to 65N in latitude and 25E to 30E in longitude. I pulled the monthly temperature anomaly values for that gridcell from a download of the CRUTEM3v file, per instructions on the linked page. For each year, the values for months 1 to 12 were averaged to create an annual average. These yearly values are what are graphed above.

Mann08 divided the 1850-1995 instrumental record into two calibration/validation intervals. Page 15253/4:

We evaluated the fidelity of reconstructions through validation experiments (see Methods), focusing here on NH land temperature reconstructions... The CPS and EIV methods... are both observed to yield reconstructions that, in general, agree with the withheld segment of the instrumental record within estimated uncertainties based on both the early (1850–1949) calibration/late (1950–1995) validation and late (1896–1995) calibration/early (1850–1895) validation.

2 comments:

  1. Ari does not seem to understand the issue at all.

    He misrepresents McIntyre. Ari says
    "The graphs he presents just show how the data is in the TEA and in the input of the MEA reconstruction so basically those graphs just show that MEA have not flipped the data upside-down before feeding it to their analysis, which is exactly the opposite that McIntyre claims to be the case. "
    But McIntyre does not say that MEA flipped the data before feeding it in. He says that the Mannomatic algorithm flips it internally.

    Mcintyre says:

    "For critics visiting this site, there isn’t a shred of doubt that Mann et al 2008 used these proxies upside down from the Tiljander interpretation. See the original post here for details. My interpretation was triple checked by two Finnish statistics professionals (Jean S and UC) who are intimately familiar with Mannian methods and who confirmed using Mann’s Matlab code that the Tiljander series are used upside down in both the CPS and EIV versions of Mann et al 2008."

    and later

    "Multivariate methods are indeed insensitive to the sign of the predictors. However, if there is a spurious correlation between temperature and sediment from bridge building and cultivation, then Mannomatic methods will seize on this spurious relationship and interpret the Tiljander sediments upside down, as we observed."

    see

    http://climateaudit.org/2009/10/14/upside-side-down-mann-and-the-peerreviewedliterature/

    Arthur Smith is correct in his comment #6.

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