SOLAR CYCLE AFFECTING EARTH'S CLIMATE
Abstract
A long uninterrupted homogeneous data set on the annual mean Sea Surface Temperature (SST) anomaly records as a representative of the Earth’s climatic parameter has been analyzed in conjunction with 158 year long time series on the annual sunspot indices, Rz and geomagnetic activity indices, aa for the period 1850–2007. The 11-year and 23-year overlapping means of global ðdtgÞ as well as northern ðdtnÞ and southern ðdtsÞ hemispheric SST anomalies reveal significant positive correlation with both Rz and aaindices. Rz, aa and dtg depict a similar trend in their long-term variation and both seem to be on increase after attaining a minimum in the early 20th century ð 1905Þ. Whereas the results on the power spectrum analysis by the Multi-Taper Method (MTM) on dtg , Rz and aa reveal periodicities of 79280 years (Gleissberg’s cycle) and 9211 years (Schwabe solar cycle) consistent with earlier findings, MTM spectrum analysis also reveals fast cycles of 3–5 years. A period of 4:2 years in aa at 99% confidence level appears recorded in dtgat 4:3 years at 90% confidence level. A period of 3:623:7 years at 99% confidence level found in dtg is correlating with a similar periodic variation in sector structure of Interplanetary Magnetic Field (IMF). This fast cycle parallelism is new and is supportive of a possible link between the solar-modulated geomagnetic activity and Earth’s climatic parameter i.e. SST.