"Cyclone activity" refers to the occurrence and movement of cyclones, which are powerful rotating storm systems characterized by strong winds and intense weather conditions. Full definition
These include droughts in Africa and North America, decline in Arctic sea - ice, changes in tropical cyclone activity in the Atlantic, and changes in the Northern Hemisphere atmospheric large - scale circulation. (usclivar.org)
Camargo, S., A.G. Barnston, and S.E. Zebiak, 2005: A statistical assessment of tropical cyclone activity in atmospheric general circulation models. (ipcc.ch)
Projected changes in the Arctic frontal zone and summer Arctic cyclone activity in the CESM Large Ensemble. (nsidc.org)