资源环境科技发展态势分析平台

The Victoria mode (VM) is defined as the second empirical orthogonal function mode (EOF2) of sea surface temperature anomalies (SSTAs) in the North Pacific north of 20 degrees N. This study examines the influence of the spring VM on the tropical cyclone (TC) genesis over the western North Pacific (WNP) during summer (May-August) for the period 1960-2016. Our analysis demonstrates that the spring VM exhibits a good relationship with the following summer tropical cyclone frequency (TCF) over the WNP, characterized by positive correlations over the eastern WNP (EWNP) and negative correlations over the western WNP (WWNP). During strongly positive VM cases, the SSTAs in the North Pacific (5 degrees-20 degrees N) associated with the spring VM persist until summer via the wind-evaporation-SST (WES) feedback. The low-level convergence (divergence) caused by the VM-related SSTAs, combined with a strengthened (weakened) WNP monsoon trough as well as a weakened (strengthened) West Pacific Subtropical High (WPSH), result in the enhanced (suppressed) TC genesis over the EWNP (WWNP). It appears that the spring VM may be a useful predictor for the WNP TCs in summer.