The BEAP Teleconnection and Its Relationship With ENSO in CMIP6: Present and Future Projections

Abstract

AbstractThis study investigates the historical simulation of the Bay of Bengal–East Asia–Pacific (BEAP) teleconnection and its relationship with the El Niño–Southern Oscillation (ENSO) using 16 models from the Coupled Model Intercomparison Project phase 6 (CMIP6). The CMIP6 models can reasonably well reproduce the BEAP‐related diabatic heating variables and the ENSO sea surface temperature anomaly (SSTA). The CMIP6 models also show good performance in simulating the BEAP pattern at subseasonal and interannual time scales. Further investigation reveals that the BEAP–ENSO relationship changes from statistically insignificant to significant on an interdecadal timescale. Significant BEAP–ENSO correlation is associated with more positive SSTA over the tropical Indian Ocean (TIO) than in the period of insignificant BEAP–ENSO correlation. The positive SSTA difference acts as a heat source that intensifies the in situ atmospheric convection to generate considerable diabatic heating around the BEAP source region. The covariation of the Indo‐Pacific SSTA exhibits a tripole pattern, namely positive SSTA over the TIO, negative SSTA over the tropical central‐western Pacific, and positive SSTA over the tropical eastern Pacific. The SSTA tripole pattern is ascribed to the Indo‐Pacific capacitor effect and zonal advective feedback. The surface wind stress is weaker during the period of significant BEAP–ENSO correlation than during the non‐significant BEAP–ENSO period. The surface wind stress is also identified as a crucial factor in the projected changes in the BEAP teleconnection. The results indicate that the enhanced zonal wind stress results in more positive BEAP cases in the 21st‐century projection.