Abstract

In this study, the effect of solar variability on global warming has been studied. This enables us to understand the existence of solar variability effects on temperature. Monthly, four components that may be closely associated with the climate have been studied, which are geomagnetic activity index aa, solar sunspot number Rz from 1868 - 2008, global surface temperature (GST) from 1880 - 2008 and total solar irradiance TSI from 1978 - 2003. The clear 11-year variation was found in Rz, TSI and aa due to the variation of solar activity, while the 21.3 year variation was found only in GST. It is related to the changes in the polarity of main solar magnetic field, in which the obtained result demonstrates that the interplanetary magnetic field (IMF) effect is more powered on GST. It is believed that the solar and anthropogenic greenhouse forcing are roughly equal contributions to the rise in global temperature during the recent years. Finally, the power law index (n) for Rz and TSI have a higher value than aa and GST. However, this indicates that the modulations of PSD of Rz and TSI are higher than the PSD of the others.

Key words: Geomagnetic induction, total solar irradiance, global warming.