  Studies on Sun-climate connection have been carried out for several decades,
and almost all of them focused on the effects of solar total irradiation
energy. As the second major terrestrial energy source from outer space, the
solar wind energy flux exhibits more significant long-term variations. However,
its link to the global climate change is rarely concerned and remain a mystery.
As a fundamental and important aspect of the Earth's weather and climate
system, tropical cyclone activity has been causing more and more attentions.
Here we investigate the possible modulation of the total energy flux input from
the solar wind into the Earth's magnetosphere on the global tropical cyclone
activity during 1963--2012. From a global perspective, the accumulated cyclone
energy increases gradually since 1963 and start to decrease after 1994. Compare
to the previously frequently used parameters, e,g., the sunspot number, the
total solar irradiation, the solar F10.7 irradiation, the tropical sea surface
temperature, and the south oscillation index, the total solar wind energy flux
input exhibits a better correlation with the global tropical cyclone activity.
Furthermore, the tropical cyclones seem to be more intense with higher
geomagnetic activities. A plausible modulation mechanism is thus proposed to
link the terrestrial weather phenomenon to the seemly-unrelated solar wind
energy input.
