PhD Student in Polar Dynamical Meteorology
University of Bern, Switzerland
Closing date: 20 February 2026
The Cloud Dynamics group affiliated with the Institute of Geography (GIUB) and the Oeschger Centre for Climate Change Research (OCCR) at the University of Bern invites applications for a PhD position on constraining precipitation efficiency of large-scale deep cloud systems using water isotope observations.
The PhD candidate will investigate precipitation formation processes in midlatitude and polar deep cloud systems, such as warm conveyor belts (WCBs) and atmospheric rivers (ARs) associated with the warm sectors of extratropical cyclones. The main objective is to assess conversion efficiency (i.e. the in-cloud component of precipitation efficiency), which is a key variable regulating surface precipitation. Conversion efficiency is a summary measure for all microphysical processes in clouds that determine how much of the condensate formed in clouds grows large enough to fall out as sedimenting hydrometeors.
Conversion efficiency will be quantified for different large-scale deep cloud systems in the Southern Hemisphere. A catalogue of WCBs and ARs from the past 5–10 years, spanning a wide range of conversion efficiencies, will be used to identify the microphysical and dynamical processes that control these differences. Water isotopes will serve as an integral tracer of in-cloud conversion efficiency. The project will combine existing ground-based in-situ water isotope measurements from the Antarctic East Coast with satellite-based observations from the IASI instrument aboard Metop satellites. Additional in-situ measurements will be carried out as part of the PhD. A particular focus will be set on cloud systems that impact snow accumulation (i.e. the surface mass balance) in Antarctica. For the interpretation of the observations a hierarchy of modelling tools will be used spanning from simple moist adiabatic air parcel ascent models widely used in isotope meteorology, over trajectory-based box models to complex high-resolution numerical weather model simulations.
The PhD student will work closely with members of the Cloud Dynamics team, who study complementary aspects of precipitation efficiency. The project is embedded in the Swiss Polar Institute Flagship project DOMINO (https://swisspolar.ch/spi-funding-instruments/spi-flagship-initiatives/), which focuses on key water-cycle processes affecting Antarctic surface mass balance. Extended field campaigns are planned at the Neumayer III station, operated by the Alfred Wegener Institute (AWI) in Antarctica, in collaboration with Swiss and international partners. Additional collaboration with AWI scientists will take place through the Antarctica InSync initiative (https://www.antarctica-insync.org/).