Solar-geomagnetic activity influence on 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, R z and geomagnetic activity indices, a a for the period 1850–2007. The 11-year and 23-year overlapping means of global ( δ t g ) as well as northern ( δ t n ) and southern ( δ t s ) hemispheric SST anomalies reveal significant positive correlation with both R z and a a indices. R z , a a and δ t g 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 ( ∼ 1905 ) . Whereas the results on the power spectrum analysis by the Multi-Taper Method (MTM) on δ t g , R z and a a reveal periodicities of ∼ 79 – 80 years (Gleissberg's cycle) and ∼ 9 – 11 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 a a at 99% confidence level appears recorded in δ t g at ∼ 4.3 years at 90% confidence level. A period of ∼ 3.6 – 3.7 years at 99% confidence level found in δ t g 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.