Convective Heating Leads to Self‐Aggregation by Generating Available Potential Energy

The moisture‐entrainment‐convection (MEC) feedback posits that a moist environment favors deep convection, which further moistens the atmosphere through its associated circulation and detrainment. The MEC feedback has been proposed to be crucial to spontaneous convective aggregation. Here we test this hypothesis by performing minimal cloud‐resolving simulations, without the buoyancy effect due to water vapor, evaporation of rain, or radiative and surface‐flux feedbacks. Convection can self‐aggregate in this minimal simulation, in which the MEC feedback is active. We then switch off this feedback by relaxing moisture to its horizontal mean over a time scale of 3 hr. Convection still self‐aggregates in this mechanism‐denial experiment, suggesting that the MEC feedback is not essential to self‐aggregation. We further show that convective heating coincides with positive temperature anomalies, generating available potential energy. Therefore, we propose that this convective heating‐overturning circulation feedback can lead to spontaneous development of large‐scale circulations. Plain Language Summary Spontaneous convective organization is considered as an important physical process for the development of the Madden‐Julian oscillation and tropical cyclones. Therefore, understanding spontaneous convective organization helps better understand the initiation of the Madden‐Julian oscillation and tropical cyclones, which will likely improve their forecasts. Here we ask, what physical processes lead to spontaneous convective organization? To address this question, we test two hypotheses: (H1) The effect of environmental moisture perturbations on convection promotes spontaneous convective organization, and (H2) latent heat release in convective storms promotes spontaneous convective organization. Using a high‐resolution atmosphere model, we show that although environmental moisture condition is an important factor, latent heat release in convective storms can lead to the spontaneous development of convective organization by itself. Key Points Convective self‐aggregation can develop without the moisture‐entrainment‐convection feedback Convection can lead to self‐aggregation by heating the region of positive buoyancy anomalies Two convective aggregates are simulated in a 3‐D cloud‐resolving model