A Monte Carlo-tuned model of the flow in the NorthGRIP area 

Annals of Glaciology, Vol 35, p. 527-530, 2002 

A. Grinsted and D. Dahl-Jensen
Geofysisk Afdeling, Niels Bohr Instituttet for Astronomi, Fysik og Geofysik, Københavns Universitet

The North Greenland Icecore Project (NorthGRIP) drill site was chosen in order to obtain a good Eemian record. At the present depth, 3001 m, the Eemian interstadial has yet to be seen. Clearly the flow in this area is poorly understood and needs further investigation. After a review of specific features of the bottom topography, it is believed that the geology changes along the flowline. In order to investigate whether this explains the observed age-depth relationship at NorthGRIP, the inverse Monte Carlo method has been applied to a simple model. The inversion reveals that the main reason no Eemian is observed is a high basal melt rate (2.7 mm a-1). The melting is a consequence of a higher geothermal heat flux than the expected 51 mW m-2 of the Precambrian shield. From our analyses it is concluded that the geothermal heat flux at NorthGRIP is 98 mW m-2. The high basal melt rate also gives rise to sliding at the bed. In addition to these results, an accumulation model has been established specifically for NorthGRIP. These results are essential for further modelling of the NorthGRIP flow and depth-age relationship.