A multi-model approach for more realistic simulations of the Greenland ice sheet during the last glacial cycle

Realistic simulations of large ice sheets under various climate conditions are crucial to estimate future ice sheet (in)stability and melt. Here, we focus on the Greenland ice sheet and its evolution under the climate of the last glacial cycle using the ice sheet model Yelmo. Our previous work demonstrated the value of applying the layer tracer model Englacial Layer Simulation Architecture (ELSA) together with dated radiostratigraphy data to validate and calibrate the Yelmo-modeled ice sheet. 

However, an outstanding complication is that the thickness of modeled isochrones not only depends on dynamical thinning but also on the original thickness upon deposition (surface mass balance). While our earlier simulations used a simplified representation of past climates and employed a positive degree day scheme to estimate the surface mass balance, we now attempt to improve the representation of the boundary conditions by using the more detailed Bergen Snow Simulator (BESSI). BESSI simulates all surface and internal fluxes of heat and mass explicitly and outputs surface mass balance while still being computationally efficient. 

With BESSI providing a more realistic layer deposition thickness, ELSA tracing the modeled isochronal layers, and radiostratigraphy providing reconstructed isochrones as a comparison quantity, we have a comprehensive framework to evaluate the climate input and ice dynamics of our simulations and can work towards a realistic modeled representation of the Greenland ice sheet over the last glacial cycle.