Dr. Killian Brennan

- severe convective storms

- cloud dynamics

- hail

- precipitation processes & efficiency

- water isotopes

- mesoscale transport

- high-resolution climate modeling

Studies:

2025: PhD/doctoral candidate ETH, Swiss Federal Institute of Technology

2021: Master of Science in Environmetal Sciences ETH, Swiss Federal Institute of Technology

2019: Bachelor of Sciences in Environmental Sciences, ETH, Swiss Federal Institute of Technology

Work:

2025 - now: Postdoc University of Bern, Oeschger Centre for Climate Change Research

2022 - 2025: Doctoral researcher ETH Zurich, Institute for Atmospheric and Climate Science, Zurich

2020 - 2021: Scientist MeteoSwiss, Radar, Satellite and Nowcasting division, Locarno Monti

2019 - 2020: Scientist EMPA, Air Pollution Monitoring, Laser Spectroscopy group, Dubendorf

2018 - 2019: Junior scientist ETH Zurich, Institute for Atmospheric and Climate Science, Zurich

2016 - 2019: Mathematics & physics tutor ABACUS Institute & ETH Zurich, Zurich

2013 - 2016: Independent lmmaker Brennan Studios, Neuenegg, drone pilot

2013 - 2015: R&D experimentalist & machinist Comet AG, X-ray division, Flamatt

2014 - 2015: Rescue technician, firefighter Swiss Army, Wangen an der Aare

2009 - 2013: Apprentice machinist University of Bern, Space Research & Planetary Science, Bern

Feldmann M., M. Blanc, K. P. Brennan, I. Thurnherr, P. Velasquez, O. Romppainen-Martius, and C. Schär, 2025: European supercell thunderstorms — A prevalent current threat and an increasing future hazard, doi: 10.1126/sciadv.adx0513.

Cui, R., I. Thurnherr, P. Vel´asquez, K. P. Brennan, 2024, M. Leclair, A. Mazzoleni, T. Schmid, H. Wernli, and C. Sch¨ar: A European hail and lightning climatology from an 11-year km-scale regional climate simulation, Journal of Geophysical Research Atmospheres, doi: 10.1029/2024JD042828.

Brennan, K. P., M. Sprenger, A. Walser, M. Arpagaus, and H. Wernli, 2025: An object-based and Lagrangian view on an intense hailstorm day in Switzerland as represented in COSMO-1E ensemble hindcast simulations, Weather and Climate Dynamics, doi: 10.5194/wcd-6-645-2025.

Portmann, J., M. Lainer, K. P. Brennan, M. J. de Thieulloy, M. Guidicelli, and S. Monhart, 2025: Performance assessment of drone-based photogrammetry coupled with machine- learning for the estimation of hail size distributions on the ground, Frontiers in Environmental Science, doi: 10.3389/fenvs.2025.1602917 (accepted).

Brennan, K. P., I. Thurnherr, M. Sprenger, and H. Wernli, 2025: Insights from hailstorm track analysis in European climate change simulations, Natural Hazards and Earth System Sciences, doi: 10.5194/egusphere-2025-918 (accepted).

Brennan, K. P. and L. Wilhelm, 2024: Saharan dust linked to European hail events, Atmospheric Chemistry and Physics, doi: 10.5194/egusphere-2024-3924 (accepted).

Lainer, M., K. P. Brennan, A. Hering, J. Kopp, S. Monhart, et al., 2024: Drone-based photogrammetry combined with deep-learning to estimate hail size distributions and melting of hail on the ground. Atmospheric Measurement Techniques, doi: 10.5194/amt-17-2539-2024.

Brennan, K. P., A. J. Miller, J. Wieder, C. Mignani, R. O. David, et al., 2021: Development of the drop Freezing Ice Nuclei Counter (FINC), intercomparison of droplet freezing techniques, and use of soluble lignin as an atmospheric ice nucleation standard, Atmospheric Measurement Techniques, doi: 10.5194/amt-14-3131-2021.

Brennan, K. P., R. O. David, and N. Borduas-Dedekind, 2020: Spatial and temporal variability in the ice-nucleating ability of alpine snowmelt and extension to frozen cloud fraction, Atmospheric Chemistry and Physics, doi: 10.5194/acp-20-163-2020.

David, R. O., M. Cascajo-Castresana, K. P. Brennan, M. Rösch, N. Els, et al., 2019: Development of the DRoplet Ice Nuclei Counter Zurich (DRINCZ): validation and application to field-collected snow samples, Atmospheric Measurement Techniques, doi: 10.5194/amt-12-6865-2019.