A GLOBAL VIEW OF THE RELATIONSHIP BETWEEN ENSO AND TROPICAL CYCLONE FREQUENCIES

The relationship between tropical cyclone activity and ENSO is examined for the major cyclone regions using cross correlations,spectral analysis and composite analysis of eastern equatorial Pacific sea surface temperature,the normalised monthly Southern Oscillation Index(SOI),and tropical cyclone frequencies.The closest relationship betweenthe 3-4 year ENSO period and tropical cyclone activity was found in the western North Pacific west of 160°E and there seems to be significant potential for seasonal forecasting in this region based on ENSO parameters alone.No significant relationships were found for the North Indian Ocean,and the remainder of the basins were dominated by oscillations near the quasi-biennial period.Physical explanations and forecasting of the seasonal variations in tropical cyclone numbers in these regions will need to account for the QBO as well as the 3-4 year ENSO connections.