Degree of simulated suppression of Atlantic tropical cyclones modulated by flavour of El Nino
- Author(s): Patricola, CM
- Chang, P
- Saravanan, R
- et al.
Published Web Locationhttps://www.nature.com/articles/ngeo2624
El Nino/Southern Oscillation, the dominant mode of interannual climate variability, strongly influences tropical cyclone activity. During canonical El Nino, the warm phase, Atlantic tropical cyclones are suppressed. However, the past decades have witnessed different El Nino characteristics, ranging from warming over the east Pacific cold tongue in canonical events to warming near the warm pool, known as warm pool El Nino or central Pacific El Nino. Global climate models project possible future increases in intensity of warm pool El Nino. Here we use a climate model at a resolution sufficient to explicitly simulate tropical cyclones to investigate how these flavours of El Nino may affect such cyclones. We show that Atlantic tropical cyclones are suppressed regardless of El Nino type. For the warmest 10% of each El Nino flavour, warm pool El Nino is substantially less effective at suppressing Atlantic tropical cyclones than cold tongue El Nino. However, for the same absolute warming intensity, the opposite is true. This is because less warming is required near the warm pool to satisfy the sea surface temperature threshold for deep convection, which leads to tropical cyclone suppression through vertical wind shear enhancements. We conclude that an understanding of future changes in not only location, but also intensity and frequency, of El Nino is important for forecasts and projections of Atlantic tropical cyclone activity.