Journal cover Journal topic
Climate of the Past An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 3.470 IF 3.470
  • IF 5-year value: 4.009 IF 5-year
    4.009
  • CiteScore value: 3.45 CiteScore
    3.45
  • SNIP value: 1.166 SNIP 1.166
  • IPP value: 3.28 IPP 3.28
  • SJR value: 1.929 SJR 1.929
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 64 Scimago H
    index 64
  • h5-index value: 43 h5-index 43
Volume 10, issue 4
Clim. Past, 10, 1473–1487, 2014
https://doi.org/10.5194/cp-10-1473-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.

Special issue: The Past: A Compass for Future Earth – PAGES Young Scientists...

Clim. Past, 10, 1473–1487, 2014
https://doi.org/10.5194/cp-10-1473-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 05 Aug 2014

Research article | 05 Aug 2014

Testing long-term summer temperature reconstruction based on maximum density chronologies obtained by reanalysis of tree-ring data sets from northernmost Sweden and Finland

V. V. Matskovsky1 and S. Helama2 V. V. Matskovsky and S. Helama
  • 1Institute of Geography, Russian Academy of Sciences, Moscow, Russia
  • 2Finnish Forest Research Institute, Northern Unit, Rovaniemi, Finland

Abstract. Here we analyse the maximum latewood density (MXD) chronologies of two published tree-ring data sets: one from Torneträsk region in northernmost Sweden (TORN; Melvin et al., 2013) and one from northern Fennoscandia (FENN; Esper et al., 2012). We paid particular attention to the MXD low-frequency variations to reconstruct summer (June–August, JJA) long-term temperature history. We used published methods of tree-ring standardization: regional curve standardization (RCS) combined with signal-free implementation. Comparisons with RCS chronologies produced using single and multiple (non-climatic) ageing curves (to be removed from the initial MXD series) were also carried out. We develop a novel method of standardization, the correction implementation of signal-free standardization, tailored for detection of pure low-frequency signal in tree-ring chronologies. In this method, the error in RCS chronology with signal-free implementation is analytically assessed and extracted to produce an advanced chronology. The importance of correction becomes obvious at lower frequencies as smoothed chronologies become progressively more correlative with correction implementation. Subsampling the FENN data to mimic the lower chronology sample size of TORN data shows that the chronologies bifurcate during the 7th, 9th, 17th and 20th centuries. We used the two MXD data sets to reconstruct summer temperature variations over the period 8 BC through AD 2010. Our new reconstruction shows multi-decadal to multi-centennial variability with changes in the amplitude of the summer temperature of 2.2 °C on average during the Common Era. Although the MXD data provide palaeoclimate research with a highly reliable summer temperature proxy, the bifurcating dendroclimatic signals identified in the two data sets imply that future research should aim at a more advanced understanding of MXD data on distinct issues: (1) influence of past population density variations on MXD production, (2) potential biases when calibrating differently produced MXD data to produce one proxy record, (3) influence of the biological age of MXD data when introducing young trees into the chronology over the most recent past and (4) possible role of waterlogging in MXD production when analysing tree-ring data of riparian trees.

Publications Copernicus
Download
Citation