This study focuses on the influence of the North Pacific Victoria mode (VM) on the persistence of the sea surface temperature anomalies (SSTAs) of El Niño–Southern Oscillation (ENSO). Both observational data and outputs from phases 5 and 6 of the Coupled Model Intercomparison Project show that VM events can enhance the persistence of ENSO SSTAs and reduce the intensity of the spring persistence barrier (SPB) of ENSO SSTAs. The possible reasons for these phenomena are that the SSTAs develop (decay) slowly and do not experience a rapid sign reversal during their decaying phase, indicating a relatively weak ENSO SPB occurs in the spring for strong VM cases. However, during weak VM cases, they transit quickly from positive (negative) SSTAs into negative (positive) SSTAs. The amplitudes of the SSTAs during weak VM cases are relatively greater in the mature phase than those during strong VM cases, resulting in a relatively strong ENSO SPB. Furthermore, VM events can affect the strength of the westerly wind anomalies over the western Pacific. The magnitude of the westerly wind anomalies is weaker when a strong ENSO co‐occurs with a strong VM event than when it is associated with a weak VM event. In addition, the subsurface water during the strong VM case transits slowly from positive to negative while that transits relatively fast during weak VM cases, which are consistent with the evolutions of SSTAs. Thus, they together affect the recharge/discharge oscillation process of ENSO, which eventually lead to a strong or a weak ENSO SPB phenomenon occurring in the spring during strong or weak VM cases, respectively. The findings offer a new sight for studying the persistence of ENSO SSTAs.
Using the observational data and the Coupled Model Intercomparison Project phase 5 (CMIP5) models this study examined the influence of the North Pacific Victoria mode (VM) on the Madden–Julian Oscillation (MJO). The results show that the February–April VM had a significant influence on the development and propagation of the MJO over the equatorial central-western Pacific (ECWP) during spring (March-May) between 1979 and 2017. Specifically, MJO development was favored more by positive VM events than negative VM events. These complicated connections could have been caused by the SST gradient anomalies associated with positive VM events, enhancing the convergence of low-level over the ECWP. When this is combined with warm SST anomalies in the equatorial central Pacific it could have led to a boost in the Kelvin wave anomalies, resulting in enhanced MJO activity over the ECWP. These conclusions indicate that the VM is an important factor in MJO diversity.
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