Implemetation of fuzzy logic on magnetic bering model
Abstract
Spectral analysis using wavelet, Lomb–Scargle and maximum entropy techniques of the proxy rainfall
record of northeastern South Africa based on annual carbon isotope (δ13C) data obtained from baobab
trees for the period 1600 AD – 2000 AD 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 cycle, the ~22-year Hale cycle as well as the 80–110-year Gleissberg cycle. A Morlet wavelet
analysis of the δ13C data between 1600 AD and 1700 AD shows the effect of the Maunder sunspot
minimum on both the Schwabe and Hale cycles during this time.
Significance:
A spectral analysis of δ13C baobab tree ring data for southern Africa between 1600 AD and 2000 AD is
presented. The results show – for the first time – that the δ13C time series contains the 11-year Schwabe,
22-year Hale as well as the 80–110-year Gleissberg solar periodicities. In addition, the influence of the
Maunder sunspot minimum between ~1650 AD and 1715 AD could also be clearly identified in the δ13C
data for the first time. These findings are of significant importance to investigations of solar influences on
climate variability
URI
http://hdl.handle.net/10394/35553https://www.sajs.co.za/article/view/6813/10299
https://doi.org/10.17159/sajs.2020/6813