Seasonality of interbasin SST contributions to Atlantic tropical cyclone
activity
Abstract
Recent studies have demonstrated that the difference in sea surface
temperature anomalies (SSTAs) between the tropical Atlantic main
development region (MDR) and the tropical Pacific (Niño 3) modulates
Atlantic tropical cyclone activity. This study further explores the
seasonality of Pacific and Atlantic contributions to Atlantic hurricane
activity. Our analysis shows that while MDR and Niño 3 SSTAs are equally
important for late-season (September-November) activity, early-season
(June-August) activity is largely modulated by MDR SSTAs. This reflects
the increased (reduced) variance of MDR (Niño 3) SSTAs in the
early-season due to their phase locking to the seasonal cycle. Further
analysis yields skillful forecasts using an MDR-Niño 3 interbasin index
derived from hindcasts of the North American Multi-Model Ensemble with
May initial conditions. However, the prediction skill for MDR SSTAs is
lower than that of Niño 3 SSTAs, suggesting that increasing the
prediction skill for MDR SSTAs is key to improving seasonal outlooks.