Differences in the destructiveness of tropical cyclones over the western North Pacific between slow- A nd rapid-transforming El Niño years

Abstract

The relationship between the destructive potential of tropical cyclones (TCs) over the western North Pacific (WNP) (as quantified by the Power Dissipation Index) and El Niño events is investigated in this work. Results show that the destructive potential of TCs is significantly affected by how rapidly El Niño decays from a positive phase to a negative phase. For TCs occurring during 'slow-transforming' El Niño, more of them initiate over the southeastern part (0°-15 °N, 150 °E-180°) of the WNP and the destructive potential of TCs is usually strong. In contrast, weaker destructiveness is indicated during 'rapid-transforming' periods, with fewer TC formations in the southeastern area. This weaker destructiveness during rapid-transforming El Niño years is mainly caused by anomalously cooler upper-ocean conditions in the central Pacific, negative relative vorticity anomalies, and increased vertical wind shear in the WNP. These findings may have important implications for the seasonal prediction of TC changes in the WNP.