Previous research showed that radiative feedbacks are essential to the
spontaneous development of convective aggregation (CSA) in idealized
atmosphere models. We find that the contribution of radiative feedbacks
decreases with warming and that, in warm climates, CSA occurs without
radiative feedbacks. We perform 2D simulations in different climates
using a cloud-resolving model and use a local moist static energy (LMSE)
framework to quantify the contribution of radiative feedbacks to the
increase of LMSE variance, which characterizes the development of CSA.
The result shows that radiative contribution dominates the LMSE variance
production when SST is less than 300 K; when SST is higher than 300 K,
adiabatic variance production becomes more important than radiative
production. Then we turn off radiative feedbacks by horizontally
homogenizing radiative heating rates at all model levels. CSA still
occurs in warmer climates (310–320 K). This result agrees with the LMSE
diagnosis and additional 3D simulations.