United States and Caribbean tropical cyclone activity related to the solar cycle

The recent increase in the power of Atlantic tropical cyclones is attributable to greater oceanic warmth in part due to anthropogenic increases in radiative forcing from greenhouse gases. However solar activity may directly influence a hurricane's power as well. Here we report on a finding that Caribbean tropical cyclone activity and U.S. hurricane counts have a pronounced 10-year periodicity with tropical cyclone intensities inversely correlated with sunspot number on the interannual and daily time scales. The finding is in accord with the heat-engine theory of hurricanes that predicts a reduction in the maximum potential intensity with a warming in the layer above the hurricane. An active sun warms the lower stratosphere through ozone absorption of additional ultraviolet (UV) radiation. Since the dissipation of the hurricane's energy occurs through ocean mixing and atmospheric transport, tropical cyclones can act to amplify a relatively small change in the sun's output appreciably altering the climate. The study has serious implications for life and property throughout the Caribbean, Mexico, and portions of the United States.