ENSO and Tropical Cyclones

One of ENSO’s most important influences is its worldwide modulation of tropical cyclone (TC) activity. TCs impact millions of people annually and can devastate life and property. Because TC attributes (e.g. genesis, track and landfall locations, intensity) are largely controlled by large-scale environmental conditions, TC activity can be substantially altered by ENSO, via ENSO’s strong modulation on both the atmosphere and ocean. Atmospheric modulations include changes in vertical wind shear, humidity, low-level vorticity, and the strength and position of subtropical highs. The ocean influences TCs via changes in sea-surface temperature and upper-ocean heat content and structure. This chapter will focus on ENSO’s influences on TC basins around the globe, including local effects and remote influences via teleconnections. These basins include the western North Pacific, central eastern North Pacific, North Atlantic, North Indian Ocean, and Southern Hemisphere (South Pacific and South Indian Ocean). We will also discuss additional factors that, together with ENSO, are important for TC prediction and projection, including other modes of natural climate variability and anthropogenic climate change.