A Study Of The Effects Of The North Pacific Victorian Mode On Intraseasonal Oscillations Of The Tropical Atmosphere

As the one of the most important mode of intraseasonal variability in the tropics,the Madden–Julian oscillation(MJO)has a momentous academic value on many short-term weather and climate phenomena globally.Many previous theoretical studies about MJO have point out a few obvious natures of the MJO,which are its large-scale convective disturbance,the time scale between a month and a season,and the eastward propagation at ?5 m/s.Although being the subject of comprehensive investigation in recent decades,accurate mode simulation and prediction of the MJO remain elusive.This study has examined the connection between the FMA VM and the following MAM MJO activity over the ECWP.This study shows that the atmospheric variations related to the VM may be one of the significant factors affecting MJO activity.The ECWP appears to be more beneficial for MJO propagation during positive VM events than during negative VM events.During positive VM events,the evolution and persistence of MJO is stronger over the ECWP,while negative VM propagates are opposite,which proves our conclusion well.We also found that the VM may be an important factor responsible for MJO diversity.The schematic model shows the processes by which the FMA VM might affect the following MAM MJO activity.One possible description for these connections is that the SST gradient anomalies associated with positive VM events enhance low-level convergence over the ECWP.Meanwhile,SSTA forcing in the CP enhances the Kelvin wave anomalies.As a result,MJO development is favored in aforesaid region.This hypothesis has certain MJO theoretical support,such as wave-CISK and MJO moisture mode theories,which point out that the MJO is strongly dependent on the accumulation of moisture in the low-level.These conclusions indicate that the VM is an important factor in MJO.