Emission location affects impacts on atmosphere and climate from alternative fuels for Norwegian domestic aviation

Aviation emissions contribute to climate change and local air pollution, with important contributions from non-CO${}_2$ emissions. These exhibit diverse impacts on atmospheric chemistry and radiative forcing (RF), varying with location, altitude, and time. Assessments of local mitigation strategies with global emission metrics may overlook this variability, but detailed studies of aviation emissions in areas smaller than continents are scarce. Integrating the AviTeam emission model and OsloCTM3, we quantify CO${}_2$, NO${}_x$, BC, OC, and SO${}_x$ emissions, tropospheric concentration changes, RF, region-specific metrics, and assess alternative fuels for Norwegian domestic aviation. Mitigation potentials for a fuel switch to LH2 differ by up to $3.1\times 10^8$  kgCO${}_2$-equivalents (GWP20) when using region-specific compared to global metrics. These differences result from a lower, region-specific contribution of non-CO${}_2$ emissions, particularly related to NO${}_x$. This study underscores the importance of accounting for non-CO${}_2$ variability in regional assessments, whether through region-specific metrics or advanced atmospheric modelling techniques.