The Role of Large Scale Waves on Moist Tropical Heat Waves

Tropical heatwaves (HWs) pose a significant threat to the population residing in the tropics and subtropics, yet their physical mechanisms are not well understood. Most research on HWs focuses on the role of temperature advection, adiabatic, and diabatic processes. However, this approach doesn’t take into account the role of moisture and deep convection in HWs, especially those that occur within the tropics. Recently, the wet bulb temperature has been adopted to account for the moisture in extreme HW events. Recent studies have found that the suppression of deep convection by dry air entrainment can account for tropical wet bulb temperature extremes. In this study, we expand upon these studies by examining the potential role the Madden-Julian Oscillation (MJO) may have on the modulation of moist tropical HW occurrence. We find that there is prominent connection between the MJO and HWs in Australia, as well as South America and South Africa. However, a large portion of the HWs tend to lag the MJO suppressed phase, suggesting that dry air alone is not responsible for a HW. This lag is examined in further detail using the moisture and moist static energy budget.