Abstract

Convective cloud systems in the maritime tropics play a critical role in global climate, but accurately representing aerosol interactions within these clouds persists as a major challenge for weather and climate modelling. The importance of ice-nucleating particles (INP), aerosols which can catalyse the freezing of cloud droplets, for tropical deep convection has been examined. Firstly, simulations of a complex tropical convective cloud field were conducted using a regional model with advanced double-moment microphysics. The radiative properties of the cloud field are very sensitive to the chosen representation of INP . In particular, the temperature dependence of the INP number concentrations, which is affected by aerosol source and composition, is a key determinant of the cloud field radiative properties. Secondly, statistical emulation of simulations of an idealised deep convective cloud was carried out. The anvil of the idealised deep convective cloud, including anvil ice crystal number concentration and anvil extent (both of which have important climate impacts), are extremely sensitive to the INP number concentrations across the entirety of the mixed-phase temperature spectrum. The results have implications for climate model simulations of tropical clouds and radiation, which generally do not consider a link between INP particle type and ice water content. The results also highlight the importance of quantifying the full spectrum of INP number concentrations across all mixed-phase altitudes, something that is logistically and technically challenging.