Response of an Arctic Mixed‐Phase Cloud to Ice‐Nucleating Particle Perturbations and Warming

Abstract The Arctic is warming faster than any other region on Earth. This warming affects Arctic clouds, both directly and through changes in aerosol concentrations, triggering feedbacks that may further amplify the warming. Here we present simulations of a wintertime cloud case from Ny‐Ålesund with parameterizations optimized for representing secondary ice production (SIP). We compare cloud phase and its impact on radiation in present‐day conditions with simulations where we perturb (a) ice‐nucleating particle concentrations (INPC) and (b) atmospheric and surface temperatures using a pseudo‐global‐warming approach. Increasing the INPC leads to cloud thinning and reduced downward longwave radiation at the surface (SDLR). Intriguingly, with warming we find an increase in cloud ice due to increased rime splintering (RS) and subsequent SIP, which also leads to reduced SDLR. This can be explained by an upward shift in the temperature region where RS is active to higher altitudes where more liquid water is present.