The Global Influence of ENSO on Rapid Intensification of Tropical Cyclones

Tropical cyclone (TC) rapid intensification (RI) is a major source of uncertainty in TC prediction. Here we examine observed basin-specific relationships between RI and El Niño-Southern Oscillation (ENSO), where RI is defined as a TC strengthening by ≥30 kt within 24 hr. During El Niño, the number of RI events significantly increases in the eastern North Pacific, western North Pacific and South Pacific, with the opposite behavior in the North Atlantic. During La Niña, changes in RI occurrence in the Atlantic and Pacific are approximately opposite as in El Niño. The ENSO–Indian Ocean RI relationship is weak. These changes are consistent with environmental conditions modulating RI, including mid-level moisture, vertical wind shear, sea surface temperatures and potential intensity. Because of disagreement between the recently observed La Nina-like trend and an El Niño-like trend simulated by climate models, improved model representation of ENSO could reduce future uncertainty in RI projections.