Influence of the North Pacific Victoria Mode on the Madden–Julian Oscillation

Tao Wen,Jianping Li,Ruiqiang Ding,Yu-Heng Tseng,Xumin Li,Zhaolu Hou,Quanliang Chen

doi:10.3389/feart.2020.584001

Abstract

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.

Highlights

As one of the most important modes of intraseasonal variability in the tropics, the Madden–Julian oscillation (MJO; Hendon et al, 2007; Madden and Julian, 1971; Madden and Julian, 1972) has momentous academic value, due to its influence on short-term weather and climate phenomena globally (Lau and Chan, 1986)
The regressions of the MAM precipitation and Outgoing Longwave Radiation (OLR) anomalies onto the FMA VM index (VMI) (Figures 2C,D) show a well-defined dipole structure over the equatorial central-western Pacific (ECWP), which is consistent with the correlation patterns
As convection activity and precipitation intensity over the ECWP make an important contribution to the propagation of MJO events, we hypothesize that the Victoria mode (VM) has an intimate relationship with MJO activity in the following spring

Summary

Introduction

As one of the most important modes of intraseasonal variability in the tropics, the Madden–Julian oscillation (MJO; Hendon et al, 2007; Madden and Julian, 1971; Madden and Julian, 1972) has momentous academic value, due to its influence on short-term weather and climate phenomena globally (Lau and Chan, 1986). Many previous theoretical studies on MJO have indicated a few obvious natures, including its large-scale convective disturbance, the time scale between a month and a season, and the eastward propagation at ∼5 m/s (Weickmann, 1983). It has been the subject of comprehensive investigation in recent decades, accurate mode simulation and prediction of the MJO remain elusive (Adames and Wallace, 2014). This study examined whether there is a fundamental connection between the FMA VM over the extratropical region following MJO activity and if there is, asking how this connection is established and exploring how it works

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Conclusion