Higher-resolution ocean and sea ice components are used in a coupled atmosphere-ocean-ice model developed for climate change simulations. The Parallel Climate Model (PCM) employs a 0.66 degree average resolution global ocean model which resolves narrow boundary currents and some eddy activity in the Arctic and North Atlantic Oceans. The dynamic-thermodynamic sea ice model uses a 27-km grid in both hemispheres, using the elastic-viscous-plastic dynamic rheology. The PCM is designed for parallel-processor computers, so higher resolution grids can be used on the increasing numbers of processors on these machines. ---- The simulations with the ocean and sea ice components of PCM, forced by prescribed atmospheric forcing, show improvements in many currents over those of previous climate models. Eddy activity in the Gulf Stream, Kuroshio, and in the Arctic-Beaufort Gyre are evident. Deep boundary currents in the N. Atlantic and other oceans are resolved as part of the global thermohaline circulation.
The effects of sea-ice transport, river runoff, and ice extent variability on global thermohaline circulation are examined. Meridional ice transport in the Southern Ocean contributes to Antarctic Bottom Water formation and strengthens the circumpolar current. Arctic river runoff and sea ice transport contribute fresh water to the subpolar N. Atlantic which weakens convective overturning and the deep boundary currents that comprise the conveyor belt. These effects have implications for simulations of climate change, in which river runoff and sea ice transport are likely to change, and resultant changes in thermohaline circulation have strong effects on climate