Intensified Deep Convection Over the Asian-Australian Monsoon Regions May Prolong the Persistence of the El Niño and La Niña Events

Relationship between the deep convection heating over the Asian-Australian monsoon regions and the El Niño Southern Oscillation (ENSO) is investigated by using the NCAR Community Earth System Model (CESM). Results indicate that the deep convection heating over the Asian-Australian monsoon regions has a strong link to the persistence of the ENSO events. Specifically, in the strong convection experiment, El Niño events and La Niña events persist 2.6 months and 2.3 months longer on average than those in the control experiment. Surface wind analysis indicates that the stronger monsoon convection expands the equatorial westerlies in meridional direction, which causes a meridionally weaker zonal wind shear. The weaker shear weakens thermocline feedback via feeble recharge/discharge feedback, which in turn prolongs the persistence of the ENSO events.