Numerical Simulations of Arctic Surface Ocean Properties: Does Floating Ice Matter?

The Arctic ocean mixed layer is a dynamic region where momentum, heat and salt fluxes are influenced by presence of seasonal sea-ice. Recent studies have brought particular focus to secular changes in freshwater content, ocean fetch, sea ice drift velocity, and the interactions between sea ice and ocean swell. These processes that take place in seasonally ice-covered waters represent a particular challenge for coupled air-sea-ice modeling. In the MITgcm, a tradeoff has emerged between realistic or the so-called “floating” ice formulation, and the more commonly used “levitating” ice formulation. The levitating formulation avoids changes in the ocean grid and is less-prone to instabilities, but it potentially sacrifices realism by not conserving freshwater and eliminating the effect of sea ice pressure on the water surface. In this study we explored the effect that these two formulations have on reproducing the recent dramatic changes in the Beaufort Gyre. We use Regional Arctic Configuration of MITgcm with different ice-physics -levitating vs. floating to explore how the freshwater buildup , Ekman circulation, and the marginal ice zone evolve using these two formulations We discuss the practical challenges of utilizing the floating ice model, and we compare the results of these two simulation with data from Ice-tethered profilers and current meters on top 200 meters of the Beaufort Gyre. We discuss the results in the context of using regional models to predict future changes to the Arctic marginal ice zone.