Long-term variations of different solar source activities and large geomagnetic disturbances also termed as geomagnetic storms (GMSs) which are associated with D st decreases of more than 100 nT, and are observed during the period 1997-2011 have been analysed. It is found that 93 large GMSs falling in our selection criteria. We have established long-term variability of above selected 93 large GMSs with different solar source activities that provides a better aspect to understand the

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... r phenomenon. Long-term variation of sudden storm commencement (SSCs) for solar cycle 21-23 shows that annually occurred value of SSCs follows with sunspot number (SSN) during the period of solar cycle 22 and 23, but solar cycle 21 is exceptional among them. Long-term variation of Kleczek solar flare index (SFI) with annual mean SSN for the period 1976-2007 shows that the yearly occurred value of SFI varies with 11-year sunspot cycle. Long-term variation of solar radio flux (SRF) with annual mean SSN for the period 1976-2011, shows that the yearly occurred value of SRF varies with 11-year sunspot cycle as similar as variation of other solar transients. The long-term solar irradiance variations (TSI) have shown that the Sun has a slight cooling trend since 1976. Various space weather condition and climatic change have also been analysed.