The Centennial Gleissberg Cycle in space weather.

A 90-100 year cycle in the sunspot number, geomagnetic activity, occurrence of midlatitude auroras and large fluence Solar Energetic Particle events has been widely reported. However the importance of this cycle, which we call the Centennial Gleissberg Cycle (CGC), for Space Weather had not received proper attention until the recent occurrence of the deep minimum during the transition from the 23rd to 24th 11-year solar cycle. This deep minimum validated the earlier CGC minima that occurred in the beginning of the 20th century and 19th century (the Dalton minimum). In this note we will describe the CGC patterns of variation in sunspot numbers, geomagnetic activity and auroras and the observed effects on the frequency and intensity of Space Weather events. We will also comment on what this implies for Space Weather during the next 30 years. [ABSTRACT FROM AUTHOR]