Jan Nitzbon

Supervisor: Dr. Julia Boike (AWI)

Project: Representation of permafrost landscape dynamics in land surface models

Large-scale Earth system and land surface models often lack an adequate representation of subgrid-scale processes. This is particularly problematic in heterogeneous permafrost landscapes where small-scale processes such as thermokarst formation might considerably impact the energy and carbon budgets in a way, for which large-scale models cannot account. Since a spatially high-resolved simulation of such processes is not feasible, novel techniques for up-scaling such processes are demanded.

Within this work a one-dimensional model of the ground thermal regime of land surfaces, CryoGrid 3, is employed to conceptually represent small-scale features of permafrost landscapes, particularly those related to thermokarst. Using tiling approaches point-wise realizations can be up-scaled in a statistical way in order to represent larger land surface units.

The model development is closely linked to field campaigns to the Lena River Delta in Siberia which offers very diverse land surface features such as polygonal tundra and thermos-erosional valleys. These features are related to the region’s diverse soil stratigraphies, in particular the occurrence of ice-rich ground. Combining field measurements with modelling will improve the qualitative and quantitative understanding of typical geomorphological processes in permafrost landscapes and advance their representation in Earth system models.