Stefanie Weißbach, PhD
PhD project title: Improved interpretation of stable water isotope signals in snow and ice from northern Greenland
Throughout the water cycle, water changes its isotope composition continuously. Therefore the stable water isotopes in an ice core show a seasonal signal. At lower temperatures the lighter isotopes are more abundant than at warmer temperatures (Dansgaard 1964).
In my PhD work I focus on the δ18O signal from a set of 13 shallow inter mediate depth (100-150 m) ice cores drilled during the AWI-North Greenland traverse (NGT) in the 1990s covering 500 to 1000 years back in time. These ice cores offer the possibility to assess regional representativeness of the NEEM record over that time interval.
Due to remoteness of northern Greenland, there is less information on the accumulation and temperature history from in-situ measurements. The stable water isotope records from NGT cores provide great information on the evolution of accumulation and temperature during the past 500 to 1000 years in north Greenland. One important topic of this study is the temperature after volcanic eruptions. Due to the great amount of aerosols after such events, the sunlight seems to be dimmed and temperatures drop.
In ice cores the seasonality of stable water isotopes can be used to date the cores. However snow pit studies in Antarctica show, that the isotopic signal in snow appears to be too periodical compared with their depositional events. A comparison of isotope signal and deposition events from snow pits around the Kohnen Station in Antarctica will be done to show whether the seasonality of stable water isotopes in the snow is a depositional signal or whether it is post-depositional, perhaps due to metamorphism in the snow.
W. Dansgaard. (1964) Stable isotopes in precipitation Tellus XVI, 4, 436-468
Start of doctoral thesis: 1st October 2011
Defence of dotoral thesis: 13th July 2016 (view thesis)
Supervisor: Prof. Dr. Heinz Miller
Co-Supervisor: Dr. Anna Wegener, Dr. Sepp Kipfstuhl
Further Members: Dr. Martin Werner, Dr. Thomas Laepple, Dr. Hans Oerter, Dr. Johannes Freitag
Cooperation with: Dr. Martin Schneebeli (SLF, Davos)
Presentations & Publications:
- Weißbach, S., Wegner, A., Opel, T., Oerter, H., Vinther, B. M., and Kipfstuhl, S.: Spatial and temporal oxygen isotope variability in northern Greenland – implications for a new climate record over the past millennium, Clim. Past, 12, 171-188, doi:10.5194/cp-12-171-2016, 2016.
- Davos Atmosphere and Cryosphere Assembly (DACA) 2013, poster presentation: "Spatial variability of δ18 O during the past 1000 years in Northern Greenland", Davos, Switzerland, 8-12 July 2013
- EGU General Assembly 2012, poster presentation: "The influence of impurities on the densification of firn -a case study from North Greenland", Vienna, Austria, 22 April 2012 - 27 April 2012
AntarktisExpedition (CoFi AP 12/13 (Coldest Firn associated projects), Kohnen Station, Alfred-Wegener Institute, 26.11.2012 - 31.01.2013)
2012 Karthaus Summer School on Glaciers and Ice Sheets in the Climate System, 12 - 21 September 2012, Italy