Speaker
Description
Annual carbon isotope (δ13C) data obtained from the Pafuri Baobab trees from north-eastern Southern Africa for the period 1200 AD – 2000 AD were used to investigate the presence and variability of the Hale, Schwabe and Gleissberg solar periodicities during the Wolf (1280 – 1340 AD), Spörer (1388 – 1550 AD), Maunder (1621 – 1715 AD) and Dalton (1790 – 1820 AD) solar minima. Spectral analysis using Morlet wavelets, Lomb-Scargle and Maximum Entropy techniques of the proxy rainfall record of north-eastern South Africa based on annual carbon isotope (δ13C) data show clear evidence of the presence of characteristic solar periodicities. Solar periodicities that were identified above the 95% confidence level include the ~ 11-year Schwabe as well as the ~ 22-year Hale cycles. In this presentation it will be shown that considerable variation in the power of the 11-year Schwabe, the 22-year Hale as well as the 80-year Gleissberg cycles exist in the δ13C proxy summer rainfall data for Southern Africa during the respective solar sunspot minima. The findings in this investigation provide clear evidence of the influence of solar activity on the climate of the Southern Hemisphere. In contrast, most previous solar-climate interaction results were based on Northern Hemisphere data sets.
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