Idealized simulations reveal the potential for widespread high supersaturation in marine tropical deep convection

Aerosols within tropical deep convective clouds (DCCs) govern in-cloud vapor supersaturation (S) and latent heating, yet the magnitude and controls of S remain poorly constrained. Using a 2000-bin spectral parcel model, we systematically quantify how the interplay among cloud condensation nuclei (CCN), ultrafine aerosol particles (UAP), and giant CCN (GCCN) regulates S. Results reveal two distinct regimes: low-S conditions in polluted air where abundant droplets efficiently deplete vapor, and high-S conditions in clean, GCCN-rich environments where coalescence reduces condensation sink, allowing S to exceed well above 10%. Secondary activation of UAP aloft suppresses S, while updraft speed exerts a non-monotonic effect controlled by residence time. Simulations using observed marine aerosol spectra reproduce high S values (∼12%), supporting their physical realism over pristine tropical oceans. These findings clarify the microphysical basis of aerosol–convective invigoration and highlight high-S regimes as critical targets for observational validation and model improvement.