  High-resolution regional hindcasting of ocean and sea ice plays an important
role in the assessment of shipping and operational risks in the Arctic Ocean.
The ice-ocean model NEMO-LIM3 was modified to improve its simulation quality
for appropriate spatio-temporal resolutions. A multigrid model setup with
connected coarse- (14 km) and fine-resolution (5 km) model configurations was
devised. These two configurations were implemented and run separately. The
resulting computational cost was lower when compared to that of the built-in
AGRIF nesting system. Ice and tracer boundary-condition schemes were modified
to achieve the correct interaction between coarse- and fine grids through a
long ice-covered open boundary. An ice-restoring scheme was implemented to
reduce spin-up time. The NEMO-LIM3 configuration described in this article
provides more flexible and customisable tools for high-resolution regional
Arctic simulations.
