Relationship between ENSO and North Atlantic tropical cyclone frequency simulated in a coupled general circulation model

Abstract

Relationship between El Niño / Southern Oscillation (ENSO) and tropical cyclone (TC) frequency over the North Atlantic simulated in a high-resolution (T213) coupled ocean-atmosphere general circulation model is described. The high-resolution model succeeded to simulate TCs with a maximum surface wind speed at 10m more than 17 m/s. In La Niña (El Niño) years, the annual number of model TCs as well as hurricanes in the North Atlantic increases (decreases). The change seems to be related to that in the vertical wind shear over the North Atlantic accompanied by model ENSO. This relationship between ENSO and North Atlantic TC frequency is in agreement with observational evidence. Although there is no TCs with a maximum surface wind more than 43 m/s belonging to the category 2 on the Saffir-Simpson scale in this model, the present study suggests that a finer-resolution CGCM could become a powerful tool for understanding the future variability of TC intensity. © 2009 Springer-Verlag US.