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Ice nucleation representation and its impact on the anthropogenic aerosol forcing in E3SM

Presentation Date
Friday, December 15, 2023 at 8:30am - Friday, December 15, 2023 at 12:50pm
MC - Poster Hall A-C - South



Ice-containing clouds play an important role in regulating the Earth's radiative budget. Ice nucleating particles (INPs) initiate ice crystal formation and affect the microphysical properties of both ice clouds and supercooled liquid clouds. However, the representation of ice nucleation in global aerosol-climate models still has large uncertainties and its impact on simulated anthropogenic aerosol forcing is not well quantified. In this study, we investigate the impact of changing ice nucleation parameterizations on the simulated ice clouds in the DOE’s Energy Exascale Earth System Model (E3SM) and assess the impact on the anthropogenic aerosol forcing estimate. We find that changes in homogenous ice nucleation from sulfate solution droplets have a dominant impact on the simulated anthropogenic aerosol effect on ice clouds, especially over the tropics. On the other hand, changes in the mixed-phase heterogeneous ice nucleation have a small impact on simulated ice cloud property differences between present-day and pre-industrial conditions, because the heterogeneous INP abundance is primarily determined by natural dust aerosols in the model. However, the heterogeneous ice nucleation significantly affects the simulated supercooled liquid water and the associated anthropogenic aerosol effect on mixed-phase clouds in the mid-latitude and polar regions. Our results show that for a more realistic anthropogenic aerosol forcing estimate, we need to better constrain the ice nucleation parameterizations in the global aerosol-climate models.

Funding Program Area(s)
Additional Resources:
NERSC (National Energy Research Scientific Computing Center)