The interplay of vertical velocity, ice microphysics, and radiative heating

Department of Hydrology and Atmospheric Sciences
4 pm on Thursday, March 24, 2022
Available via zoom and in-person in Harshbarger 110
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Sylvia Sullivan
Assistant Professor, Department of Chemical and Environmental Engineering, University of Arizona


With increases in computational power, a new generation of storm-resolving models is allowing us to represent atmospheric convection with unprecedented realism. Despite this breakthrough, microscale processes – particularly in-cloud ice crystal formation – can still be described only approximately. Annual-average ice crystal numbers vary by two orders of magnitude between model formulations, and we design a numerical tool to trace these differences back to inputs like vertical velocity and aerosol concentrations. This modelling challenge of cloud ice cannot be simply overlooked, as it has strong control on the radiative budget. We show this first from the Eulerian perspective of limited-area storm-resolving simulations over the Asian monsoon region and second from the Lagrangian perspective of trajectories run with different microphysics schemes. These results pinpoint several factors related to ice formation worthy of further constraint or improvement in our new generation of models.


Sylvia Sullivan is an Assistant Professor in the Department of Chemical and Environmental Engineering since January 2022. She joined the University of Arizona from the Karlsruhe Institute of Technology in Germany, where she was a Young Investigator Fellow. She completed her Bachelor of Science in Chemical Engineering in 2012 at the California Institute of Technology. In 2017, she earned her Ph.D. in Chemical Engineering at the Georgia Institute of Technology with a minor in Earth and Atmospheric Sciences and spent two years thereafter as a postdoctoral researcher in the Department of Earth and Environmental Engineering at Columbia University.