Global climate models have pointed to the polar regions as very sensitiveareas in response to climate change. However, these models often do notcontain representations of processes peculiar to the polar regions such asdynamic sea ice, permafrost, and Arctic stratus clouds. Further, globalmodels do not have the resolution necessary to model accurately many of theimportant processes and feedbacks. Thus, there is a need for regionalclimate models of higher resolution. Our such model (ARCSy M) has beendeveloped by A. Lynch and W. Chapman. This model incorporates the NCARRegional Climate Model (RegCM2) with the addition of Flato–Hibler cavitatingfluid sea-ice dynamics and Parkinson–Washington ice thermodynamicformulation. Recently work has been conducted to couple a mixed-layer oceanto the atmosphere–ice model, and a three-dimensional (3-D) dynamical oceanmodel, in this case the S-Coordinate Primitive Equation Model (SPEM), to theice model. Simulations including oceanic circulation will allowinvestigations of the feedbacks involved in fresh-water runoff from sea-icemelt and sea-ice transport. Further, it is shown that the definition of themixed-layer depth has significant impact on ice thermodynamics.

Injection of a homogeneous fluid into a linearly stratified and rotating background fluid produced anticyclonic lenses which were studied for up to 600 rotation periods. Velocity measurements showed that the interior core rotates as a solid body with a decreasing, nearly axisymmetric exterior velocity field. Gill's (1981) model predicts well both the velocity and aspect ratio vs. Rossby number of the lenses. Lens decay occurred in two stages: symmetric rapid spin-down, with an associated half-life of ≈ 70 rotation periods followed by asymmetric shedding at a nearly constant core Rossby number, Ro ≈ 0.06.