Henning Franke

Department Climate Physics
Group Wave Driven Circulations IMPRS
Position Phd Candidate
phone +49 40 41173-104
Email henning.franke@mpimet.mpg.de
Room B 405


I investigate how and why the quasi-biennial oscillation (QBO) of the zonal wind in the tropical stratosphere may change in a warming climate. Previous attempts to answer this question using conventional general circulation models (GCMs) with a typical horizontal resolution of O(100)km have been inconclusive due to huge intermodel uncertainty. The root cause of this intermodel uncertainty has been found to be the inherent uncertainty of the gravity wave parameterizations that these GCMs have to employ due to their coarse horizontal resolution.

My attempt to overcome this problem is the direct simulation of the QBO in our in-house global storm-resolving model ICON, which explicitly resolves deep convection and most parts of the atmospheric gravity wave spectrum. Consequently, the inherently uncertain parametrizations of convection and gravity waves are no longer needed and the QBO is entirely forced by resolved dynamics. This modelling approach will hopefuly allow for a more informed answer to the question of potential warming-induced changes of the QBO.

Beyond my particular interest in the QBO and its dynamics, I'm further interested also in other parts of the stratospheric general circulation. This includes the Brewer-Dobson circulation, the polar vortices and all kinds of stratospheric wave-mean flow interactions and how external forcings (e.g. volcanic eruptions or changes in greehouse gases) may impact these features of the stratospheric circulation. Furthermore, I'm interested in the dynamic coupling between the stratosphere and the troposphere and how the stratosphere can be used to gain tropospheric forecast skill.

More information

H. Franke, P. Preusse, M. A. Giorgetta: Changes of tropical gravity waves and the quasi-biennial oscillation in storm-resolving simulations of idealized global warming, Quarterly Journal of the Royal Meteorological Society, https://doi.org/10.1002/qj.4534, 2023.

I. Quaglia, C. Timmreck, U. Niemeier, D. Visioni, G. Pitari, C. Brühl, S. Dhomse, H. Franke, A. Laakso, G. Mann, E. Rozanov, T. Sukhodolov: Interactive Stratospheric Aerosol models' response to different amounts and altitudes of SO2injections during the 1991 Pinatubo eruption, Atmos. Chem. Phys.https://doi.org/10.5194/acp-23-921-2023, 2023.

M. A. Giorgetta, W. Sawyer, X. Lapillonne, P. Adamidis, D. Alexeev, V. Clément, R. Dietlicher, J. F. Engels, M. Esch, H. Franke, C. Frauen, W. M. Hannah, B. R. Hillman, L. Kornblueh, P. Marti, M. R. Norman, R. Pincus, S. Rast, D. Reinert, R. Schnur, U. Schulzweida, and B. Stevens: The ICON-A model for direct QBO simulations on GPUs (version icon-cscs:baf28a514), Geoscientific Model Developmenthttps://doi.org/10.5194/gmd-15-6985-2022, 2022.

D. K. Weisenstein, D. Visioni, H. Franke, U. Niemeier, S. Vattioni, G. Chiodo, T. Peter, and D. W. Keith: A Model Intercomparison of Stratospheric Solar Geoengineering by Accumulation-Mode Sulfate Aerosols, Atmos. Chem. Phys.https://doi.org/10.5194/acp-22-2955-2022, 2022.

H. Franke, U. Niemeier, D. Visioni: Differences in the quasi-biennial oscillation response to stratospheric aerosol modification depending on injection strategy and species, Atmos. Chem. Phys.https://doi.org/10.5194/acp-21-8615-2021, 2021.

Ph.D. Earth System Sciences, University of Hamburg (since 2020)
Topic: The quasi-biennial oscillation in a warming climate
Supervision: Dr. Marco Giorgetta, Dr. Ulrike Niemeier, Prof. Bjorn Stevens

M.Sc. Meteorology, University of Hamburg (2017 - 2020)
Master's Thesis: Stratospheric Injection of Sulfur - Injection of H2SO4 Compared to Injection of SO2
Supervision: Dr. Ulrike Niemeier, Prof. Stefan Bühler
Stay abroad: The University Centre in Svalbard (Longyearbyen, Norway), 2018

B.Sc. Meteorology, University of Hamburg (2014 - 2018)
Bachelor's Thesis: Cloud Correlations in Tropical Convection
Supervision: Dr. Jan O. Härter, Prof. Stefan Bühler
Stay abroad: University of Oklahoma (Norman, USA), 2016