Multidecadal Fluctuations in the Observed ENSO-Tropical Cyclone Teleconnection

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Multidecadal Fluctuations in the Observed ENSO-Tropical Cyclone Teleconnection

Abstract El Niño-Southern Oscillation is a skillful predictor for seasonal tropical cyclone activity in most tropical cyclone basins. This study examines recent changes in the observed ENSO-tropical cyclone teleconnection strength, as measured by ENSO modulation of hurricane frequency. We find that the ENSO-North Atlantic tropical cyclone teleconnection fluctuated over time, with the strongest relationship occurring from the nineteen eighties to the mid-two thousands. In the western and eastern North Pacific, the ENSO-tropical cyclone teleconnection has strengthened in recent decades. Periods with a strong ENSO-tropical cyclone teleconnection are associated with more favorable environmental conditions for tropical cyclones, with higher values of genesis potential indices. Positive phases of the Atlantic Multidecadal Oscillation coincided with periods of strong ENSO-tropical cyclone teleconnections in the Atlantic and North Pacific basins. A weaker Atlantic ENSO-tropical cyclone relationship was associated with negative phases of the Pacific Decadal Oscillation and the North Atlantic Oscillation. This research reveals climate conditions that modulate ENSO's utility for seasonal tropical cyclone prediction.

Plain Language Summary El Niño-Southern Oscillation is a useful predictor for seasonal tropical cyclone activity in many basins. Here we found that the strength of the ENSO-tropical cyclone teleconnection, represented as the correlation between ENSO and the number of hurricanes and accumulated cyclone energy, has changed in the historical record. The ENSO-tropical cyclone teleconnection in the North Atlantic fluctuated over time, with a weak relationship during the nineteen sixties and nineteen seventies and a strong relationship during the nineteen eighties to mid-two thousands. Meanwhile, the ENSO-tropical cyclone teleconnection strengthened in the North Pacific in recent decades, with strong teleconnections after the nineteen eighties in the western North Pacific and after the two thousands in the eastern North Pacific. Periods of strong ENSO-tropical cyclone teleconnections are associated with more favorable environmental conditions for tropical cyclones, including higher values of genesis potential indices and higher mid-tropospheric humidity, as well as positive phases of the Atlantic Multidecadal Oscillation. Additionally, the negative phase of the Pacific Decadal Oscillation leads to strong/weak ENSO-tropical cyclone teleconnections in the eastern North Pacific and North Atlantic, respectively. Furthermore, a negative North Atlantic Oscillation is associated with a weak ENSO-North Atlantic tropical cyclone teleconnection. This research highlights variations in ENSO's effectiveness for seasonal tropical cyclone prediction.