Decadal and Bi-Decadal Periodicities in Temperature of Southern Scandinavia: Manifestations of Natural Variability or Climatic Response to Solar Cycles?

Maxim Ogurtsov

doi:10.3390/atmos12060676

Abstract

Nine proxies of temperature over the last 225–300 years in Southern Fennoscandia (55–63° N) were analyzed. Seven reconstructions of the mean growing season temperatures were obtained by dendroclimatological methods. Reconstructions of spring temperatures in Stockholm and winter temperatures in Tallinn were based on historical documentary sources. It was found that significant decadal (10–13 years) and bi-decadal (22–25 years) periodicities were present in many of these series during the entire time interval. Four proxy records correlated significantly with the quasi 22-year solar cycle of Hale. Three time series correlated significantly with the quasi 11-year solar cycle of Schwabe. This can be considered as evidence of a link between decadal and bi-decadal changes in solar activity and climate in Southern Fennoscandia. On the other hand, signs of correlation differed, as well as the time shift between the solar and temperature cycles. It is difficult to explain such an intricate relationship and, thus, the physical mechanism of solar−climatic linkages remains unclear. That is why assumptions about the purely occasional appearance of correlations cannot yet be rejected. Guidelines for further research are suggested.

Highlights

The question of the reality of a relationship between solar activity and the Earth’s climate and its possible physical mechanism is becoming increasingly important in solar−terrestrial research
This work is aimed at the analysis of solar−climate relations over the southern part of Scandinavia (55–63◦ N, 10–35◦ E) during the 18th–20th centuries
The performed study showed that evidence of a solar−climatic connection exists, at Northern Fennoscandia but at Southern Fennoscandia as well

Summary

Introduction

The question of the reality of a relationship between solar activity and the Earth’s climate and its possible physical mechanism is becoming increasingly important in solar−terrestrial research. Evidence of the solar influence on the climate of Northern Fennoscandia (NF) was obtained from a number of studies, based on the data of paleoclimatology [1,2,3,4,5]. It was shown that the solar-climatic effects, if they really exist, have an apparent regional distribution [8,9,10]. That is why the study of possible solar−climatic associations in the area adjacent to NF is of great importance. Southern Fennoscandia (SF) is the region situated the closest to NF. This work is aimed at the analysis of solar−climate relations over the southern part of Scandinavia (55–63◦ N, 10–35◦ E) during the 18th–20th centuries

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