Interdecadal modulation on the relationship between ENSO and typhoon activity during the late season in the western North Pacific

Abstract

The present study identifies an interdecadal modulation of the Pacific decadal oscillation (PDO) on the relationship between El Nino-Southern oscillation (ENSO) and typhoon activity during the late season (October–December) in the western North Pacific. The PDO is uncorrelated with ENSO during the warm phase of 1979–1997, while the PDO is positively correlated with ENSO during the cold phase of 1998–2012. Further analyses show that the warm phase is associated with the reduced ENSO–typhoon activity relationship and more typhoons, whereas the cold phase is corresponded to the enhanced ENSO–typhoon activity relationship and fewer typhoons. These variations are mainly manifested by a significant difference of typhoon activity in the southeastern part of the western North Pacific. Moreover, the change of ENSO–typhoon relationship is largely due to changes in large-scale environmental conditions especially from low-level vorticity and vertical wind shear between the two phases, which are related to the changes in tropical Indo-Pacific sea surface temperature. The study implies that the phase of the PDO should be taken into account when ENSO is used as a predictor for predicting typhoon activity in the western North Pacific.