Influence of SST‐Precipitation Relationship Over the Equatorial Western Pacific on Simulation of the Madden‐Julian Oscillation

Capabilities of 43 models of the Coupled Model Intercomparison Project Phase 6 (CMIP6) to simulate the Madden‐Julian Oscillation (MJO) were compared in this study. Models with higher MJO simulation skills reproduce organized large‐scale convection more frequently over the equatorial western Pacific (EWP), suggesting that MJO simulations are tightly connected to organization of large‐scale precipitation over the EWP. MJO simulation skills are not significantly correlated with the mean sea surface temperature (SST) over the EWP, but tightly connected to SST threshold for convection there. The top simulations exhibit lower SST threshold and more realistic SST‐precipitation relationship over the EWP, suggesting that convection can be organized more efficiently and intensified more rapidly with the increasing SST in these simulations. Our results emphasize that reproducing the relationship between SST and large‐scale precipitation over the EWP is critical to MJO simulations. Plain Language Summary The Madden‐Julian Oscillation (MJO) is one of the most important tropical phenomena that modulate weather and climate systems at the intraseasonal time scales. However, accurately reproducing the MJO in global climate models remains a challenge. The eastward propagation of the MJO convection is usually not well‐reproduced in models. Comparing to observations, they tend to underestimate the occurrence frequency of individual MJO events with lower amplitude and shorter propagation range. This study explore whether the MJO simulations in models are linked to the relationship between sea surface temperature (SST) and large‐scale precipitation they reproduced. It was found that MJO simulation skills are greatly dependent on the organized large‐scale precipitation over the equatorial western Pacific. We further revealed that realistically reproducing the SST‐precipitation relationship over this region is critical for simulating the MJO in models. Key Points Madden‐Julian Oscillation (MJO) simulation skills depend on organized large‐scale precipitation over the equatorial western Pacific (EWP) reproduced in models Models with higher MJO simulation skills exhibit lower sea surface temperature (SST) threshold for convection over the EWP Realistically reproducing the relationship between the SST and organized large‐scale precipitation is critical to MJO simulations