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Abstract The Madden Julian Oscillation (MJO) consists of a tropical convective region that propagates eastward through the Indo‐Pacific warm pool. Decadal climate variability alters sea surface temperature patterns, affecting the MJO's basic state. This investigation examines the impact of projected SST and moisture pattern changes over the 21st Century on MJO precipitation and zonal wind amplitude changes in 80 members of the Community Earth System Model 2 Large Ensemble in the SSP370 radiative forcing scenario, each with its unique representation of decadal variability. Ensemble members with strongest MJO precipitation change in a given 20‐year period have a more El Niño‐like east Pacific warming pattern. MJO amplitude increases for east Pacific warming because of a strengthened meridional moisture gradient that supports MJO eastward propagation. A stronger vertical moisture gradient also exists for ensemble members with preferential east Pacific warming, which supports a stronger MJO under moisture mode theory. 

Abstract This study investigates the vertical structure and related dynamical and energy conversion processes that aided the development of two east Pacific easterly waves (EWs) during the 2019 OTREC (Organization of Tropical East Pacific Convection) campaign period. The initial mesoscale convective systems (MCSs) that seeded both disturbances formed near the Panama Bight and developed into EWs near the Papagayo jet exit region. In the MCS stage, both disturbances were characterized by top‐heavy vertical motions and midlevel vorticity near the maximum vorticity center. The deep convection caused strong latent heating and eddy available potential energy (EAPE) generation and conversion to eddy kinetic energy (EKE) in the upper levels. When the disturbances moved to the south of the Papagayo jet, they interacted with the low‐level shear vorticity there, enhancing low‐level stretching and vorticity. Subsequently, the top‐heavy upward motion intensified and led to enhanced stretching and vorticity intensification at midlevels. The enhanced stretching on the southwest side also favored the formation of southwest‐northeast tilted vorticity at midlevels that characterizes EWs. After the EWs formed near the jet exit, the vertical motion weakened and became more bottom‐heavy, with the maximum vorticity shifting to lower levels. This change in the vertical motion profile near the jet exit region is likely modulated by the lower sea surface temperature, reduced moisture, and weaker convective instability. While EAPE‐to‐EKE conversion weakened during this period, the low‐level barotropic conversion of EKE in the jet exit served as the primary energy source for the EWs. 

Abstract Anomalous tropical longwave cloud‐radiative heating of the atmosphere is generated when convective precipitation occurs, which plays an important role in the dynamics of tropical disturbances. Defining the observed cloud‐radiative feedback as the reduction of top‐of‐atmosphere longwave radiative cooling per unit precipitation, the feedback magnitudes are sensitive to the observed precipitation data set used when comparing two versions of Global Precipitation Climatology Project, version 1.3 (GPCPv1.3) and the newer version 3.2 (GPCPv3.2). GPCPv3.2 contains larger magnitudes and variance of daily precipitation, which yields a weaker cloud‐radiative feedback in tropical disturbances at all frequencies and zonal wavenumbers. Weaker cloud‐radiative feedbacks occur in GPCPv3.2 at shorter zonal lengths on intraseasonal timescales, which implies a preferential growth at planetary scales for the Madden‐Julian oscillation. Phase relationships between precipitation, radiative heating, and other thermodynamic variables in eastward‐propagating gravity waves also change with the updated GPCPv3.2.