The Temporal Variations in Sunspot Number, Geomagnetic aa index and Southern Oscillation Index

Iratius Radiman ( Department of Astronomy-FMIPA ITB)
Hiroshi Miyake ( Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan)
Chatief Kunjaya ( Department of Astronomy-FMIPA ITB)
Yoji Takeoka ( Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan)
Muhamad Irfan Hakim ( Department of Astronomy-FMIPA ITB)
Zadrach L. Dupe ( )Department of Geophysics and Meteorology-FIKTM ITB)

Jurnal Matematika & Sains
Vol 7, No 1 (2002)

A study of three monthly solar-terrestrial indices of mean sunspot number, geomagnetic aa index, and Southern Oscillation Index during period of 1882 to 2000 was carried out to find any consistent short –term periodicities. We found 19, 22, and 26-month periodicities persistently occur in the above data, i nstead of 11-year pattern. We suggest that they might have solar activity origin.