Table of Contents
Journal of Climatology
Volume 2014, Article ID 578761, 13 pages
http://dx.doi.org/10.1155/2014/578761
Research Article

Six Temperature Proxies of Scots Pine from the Interior of Northern Fennoscandia Combined in Three Frequency Ranges

1Metla, Rovaniemi Research Unit, P.O. Box 16, 96301 Rovaniemi, Finland
2A.F. Ioffe Physico-Technical Institute, St. Petersburg 194 021, Russia
3Bolin Centre for Climate Research, Department of Physical Geography and Quaternary Geology, Stockholm University, 106 91 Stockholm, Sweden

Received 20 December 2013; Revised 7 April 2014; Accepted 11 April 2014; Published 6 May 2014

Academic Editor: Silvio Gualdi

Copyright © 2014 Markus Lindholm et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Six chronologies based on the growth of Scots pine from the inland of northern Fennoscandia were built to separately enhance low, medium, and higher frequencies in growth variability in 1000–2002. Several periodicities of growth were found in common in these data. Five of the low-frequency series have a significant oscillatory mode at 200–250 years of cycle length. Most series also have strong multidecadal scale variability and significant peaks at 33, 67, or 83–125 years. Reconstruction models for mean July and June–August as well as three longer period temperatures were built and compared using stringent verification statistics. We describe main differences in model performance ( = 0.53–0.62) between individual proxies as well as their various averages depending on provenance and proxy type, length of target period, and frequency range. A separate medium-frequency chronology (a proxy for June–August temperatures) is presented, which is closely similar in amplitude and duration to the last two cycles of the Atlantic multidecadal oscillation (AMO). The good synchrony between these two series is only hampered by a 10-year difference in timing. Recognizing a strong medium-frequency component in Fennoscandian climate proxies helps to explain part of the uncertainties in their 20th century trends.