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ENSO and North Atlantic HurricanesAtlantic Hurricanes and Global Sea Surface TemperatureThe global sea surface temperatures (SSTs) have a strong influence on the hurricane activity in the Atlantic. In Figure 9, the correlation of the anomalous SST in August - October (ASO) and the number of Atlantic hurricanes in this period in shown. There is a high correlation with the local sea surface temperatures in the tropical Atlantic, which are known to influence the hurricane activity (Gray 1984). The negative correlation in the South Atlantic could be interpreted as part of the Atlantic dipole pattern, which is related to the rainfall variability in the Sahel (Folland et al. 1986 ), and Sahelian rainfall variability is thought to influence hurricane activity (Gray 1984). The correlation pattern on the North Atlantic has been related to a multidecadal variability of the Atlantic hurricane activity (Goldenberg et al. 2001). On the Pacific, an ENSO pattern appears, which influences the Atlantic hurricane activity indirectly, mainly by changes in the upper tropospheric winds in the tropical Atlantic (Gray 1984). The Pacific pattern is very similar to ENSO pattern, but less confined to the low latitudes, as the Pacific decadal oscillation (PDO) pattern (see e.g., Zhang et al. 1997; Mestas-Nuñez and Enfield 1999), so probably the Pacific pattern is a mixture of ENSO and the PDO. The negative correlation pattern in the Indian Ocean is also related to ENSO, as the Indian Ocean sea surface temperature variablity and ENSO are known to be closely related (Goddard and Graham 1999).
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