Sonja Wahl

Position

Postdoctoral Fellow, PostDoc

Affiliation

Research

My research is centered around the interaction between the fast changing atmosphere and the integrating snowpack below. I am fascinated by snow in all its varieties and study the processes affecting it such as snow metamorphism, surface energy fluxes and wind drift. Snow is archiving climatic information and I am particularly interested in how the climate signal is formed in the snow. This signal can be preserved for thousands of years and is retrieved by scientist in the form of ice cores. My work of studying present cryospheric processes will help to improve climate reconstruction efforts from such ice core climate proxy records.

Currently, I am the PI of the SnowDOGS project with collaborators at the University of Washington in the US and Le Laboratoire des Sciences du Climat et de l'Environnement in France. Until December 2024 the Earth and Space Research Institute at the University of Washington will host me for the first year of the SnowDOGS project.

Publications
  • Benjamin Walter, Hagen Weigel, Sonja Wahl, and Henning Löwe. “Wind Tunnel Experiments to Quantify the Effect of Aeolian Snow Transport on the Surface Snow Microstructure.” The Cryosphere Discussions, July 26, 2023. https://doi.org/10.5194/tc-2023-112.
Academic article
Popular scientific lecture
Other presentation
Poster
Website (informational material)
Lecture

See a complete overview of publications in Cristin.

Projects

SnowDOGS - Snow D-excess Origin Study

December 2023 - November 2026

Ice core water isotope records from the polar areas are invaluable climate proxies providing information about the relationship between the climate mean state and it's variability. The secondary ice core water isotope "excess" parameters, d-excess and 17O-excess, are especially useful for climate reconstruction since they presumably contain climatic information from the precipitation source regions. However, when simulating excess records with state-of-the-art isotope-enabled climate models, simulated and observed records disagree in seasonal to decadal signal variability.

Strikingly, the ability to simulate isotope variability in precipitation and isotope variability in ice cores is distinct, which suggests d-/17O-excess signal formation processes after deposition. Recently, it was demonstrated that post-depositional processes (PDP) can influence the snow isotopic composition, yet the impact of PDP on the ice core signal has not been quantified. Thus, PDP could be the missing link in our understanding of the transfer function between climate and ice core signal. SnowDOGS' hypothesis is thus that PDP, which are currently not implemented in climate models, define the ice core d-/17O-excess signals and overprint the original precipitation source region information.

SnowDOGS aims to quantify the impact of PDP on ice core excess signals by implementing multiple PDP in the existing Community Firn Model. Simulated d-/17O-excess records will be compared against observed ice core records from various locations on the Greenland and Antarctic Ice Sheet. SnowDOGS will clarify i) if PDP help in aligning simulated and observed isotope records, ii) to what extent PDP overprint the original source signal, and iii) what role PDP played in generating the high-frequency variability in d-/17O-excess records observed in different climate states. SnowDOGS will thus combine modeling and proxy records to improve the reconstruction and prediction of climate variability.