Global tropical cyclone activity: Link to the North Atlantic oscillation

An index of global tropical cyclone activity (GTCA) is extracted from an in terbasin dispersion matrix composed of correlations in the frequency of tro pical cyclones among the five principal basins of activity over the period 1966-1998. The extraction is performed using a single-factor common factor analysis model. Factor scores-provide the index of GTCA. The time series of factor scores is matched with annual series' of the El Nino-southern oscil lation (ENSO) and the North Atlantic oscillation (NAO) revealing a statisti cal link to the NAG, but not to the ENSO. Results suggest a greater role of high latitude atmospheric and oceanic processes in modulating tropical cyc lone climate than previously :considered.