Modeling the Impact of Alternative Fuels and Hydrogen Propulsion on Contrail‐Cirrus: A Parameter Study

Abstract

Line-shaped aircraft contrails can spread into long-lived cirrus clouds that contribute significantly to aviation-induced radiative forcing. Previous modeling studies mainly examined contrails from conventional kerosene combustion, but this study explores how hydrogen combustion changes contrail-cirrus properties using large-eddy simulations with detailed particle-based microphysics. Simulations across various atmospheric conditions and aircraft types show that total ice crystal number and mass are especially sensitive to the initial ice crystal number and ambient temperature. Fewer initially formed ice crystals lead to larger particles that sediment earlier, shortening contrail lifetime and substantially reducing radiative impact in a nonlinear way.