부산대학교 도서관

The influence of the cross‐equatorial northerly surge (CES) on the eastward propagation of Madden‐Julian oscillation (MJO) during boreal winter is evaluated through the analysis of the column integrated moisture budget. Results show that the CES reinforces MJO's southward detour by increasing horizontal moisture convergence over the southern Maritime Continent (MC) region. Further analysis reveals that the zonal convergence by intraseasonal zonal wind anomalies acting upon background moisture is intensified in the presence of CES events, causing a stronger convective activity in the southern MC (SMC). The stronger moisture convergence in the SMC is associated with the CES‐induced intensification of low‐level northwesterly and westerly winds, which, in turn, strengthen zonal wind convergences and positive wind‐evaporation feedbacks onto the MJO convection. An improved process understanding of the link between the CES and MJO detours can help engender improvements in extreme weather forecasts and aid investigation biases in simulating MJO in climate models. Plain Language Summary: Madden‐Julian oscillation (MJO) is a tropical large‐scale atmospheric phenomenon characterized by an eastward propagating band of clouds and rainfall. Sometimes, during its journey over the Maritime Continent (MC), the MJO takes a southward detour. This detour can have significant impacts on the climate and weather patterns. In this study, we explore the potential impact of a cross‐equatorial northerly cold surge (CES) on the magnitude of the MJO detour over the MC. We find that the magnitude of the MJO's southward detour becomes stronger in the presence of CES events. The CES increases northwesterly and westerly winds, which in turn enhances zonal moisture convergence and strengthens positive wind‐evaporation feedback onto MJO convection. A better understanding of the relationship between the CES and the MJO can lead to improvements in extreme weather forecasting over the MC and other regions, and aid in investigating biases in simulating MJO propagation in global climate models. Key Points: Cross‐equatorial surge (CES) amplifies Madden‐Julian oscillation (MJO)'s southward detour during the active Australian monsoon season (December–March)Zonal moisture convergence by CES wind acting upon the background moisture increases MJO convection over the southern Maritime ContinentCES‐induced intensification of low‐level northwesterly and westerly winds enhances positive wind‐evaporation feedback onto MJO convection [ABSTRACT FROM AUTHOR]