ENSO and North Atlantic Hurricanes

Introduction

The Atlantic hurricane season is influenced by different factors, among them ENSO. The influence of ENSO on Atlantic hurricanes is well known (Gray, 1984; O'Brien et al., 1996; Bove et al,. 1998). However, ENSO is not the only factor influencing Atlantic hurricane activity. Other important environmental factors varying on different time scales are, Atlantic sea surface temperatures (Landsea et al., 1999), the stratospheric Quasi-biennial oscillation (Gray, 1984), the Madden-Julian Oscillation (Maloney and Hartmann, 2000), the North Atlantic Oscillation (Elsner et al., 2000), African Easterly Waves (Avila, 1991; Avila and Pasch, 1992) and others.

In general, there are fewer Atlantic hurricanes in an El Niño year than usual, while in a La Niña year, there are more Atlantic hurricanes. However, due to the many other factors that influence hurricane genesis, this relation is not always valid. Here we give a short summary of the relation between the Atlantic hurricane season and ENSO.

Hurricane datasets have known defficiencies (Landsea, 1993). Atlantic aircraft monitoring started only in 1944 and before that short-lived tropical cyclones were likely unobserved, though the U.S. landfalling hurricanes data are reliable. Additionally, the hurricane activity in the period between 1940 and 1960 is thought to be overestimated. Continuous satellite coverage started only in the middle 1960s, so before that characteristics of most individual tropical cyclones formation are unreliable.  Here we use the Atlantic hurricane dataset from 1950 to 2001, so these deffiencies should be remembered.

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