Modelling Greenland’s subglacial hydrology using CUAS-MPI

Subglacial hydrology plays a key role in many glaciological processes. The amount of water at the glacier base and the properties of the hydraulic system modulate the basal sliding and, thus, ice discharge. The subglacial discharge of fresh water impacts the physical, chemical, and biological properties of the adjacent fjords or ice shelf cavities. It is a main driver of submarine melting and glacier terminus retreat for Greenland’s marine-terminating glaciers.

We apply the MPI-parallel implementation of the Confined-Unconfined Aquifer System model (CUAS-MPI) to the entire Greenland Ice Sheet. The model is forced with water input from ice sheet basal melt and additional runoff (daily) from the regional climate model RACMO. CUAS-MPI is based on an effective porous media approach (single-layer, Darcy-type flow) in which the hydraulic transmissivity is spatially and temporally varying. The transmissivity evolves due to channel wall melt, creep-closure, and cavity opening. This makes it possible to simulate inefficient and efficient water transport without resolving individual channels.

Based on daily model output data, we analyse the evolution of Greenland’s subglacial system and the water discharge into selected fjords and compare the results for a normal year (2018) with a particularly warm year (2019).