J. Clim. http://dx.doi.org/10.1175/2011JCLI4115.1 (2011)
Weather-dependent processes, such as disease outbreaks and terrestrial productivity, are sensitive to the variability as well as the mean state of climate parameters. Satellite data show that the variability of two such factors — solar radiation and precipitation — was correlated in recent years.
David Medvigy and Claudie Beaulieu of Princeton University examined variations in surface-level solar radiation and daily precipitation across the globe between 1984 and 2007. They found significant shifts in solar variability over 35% of the globe; shifts in precipitation variability were evident over 40% of the globe, with an increase apparent over tropical Africa and southeast Asia. Variations in solar radiation were positively correlated with variations in precipitation and the abundance of deep convective clouds in tropical regions.
Whether or not a causal link exists between solar variability, precipitation and cloud abundance, however, remains unclear.