Influences of Ice Embedding on the Ice-Sea Interaction in the Arctic Ocean: Experiments with AO-FVCOM

Ice embedding physics has been implemented into the ice-current-wave fully coupled unstructured-grid Finite-Volume Community Ocean Model (FVCOM). The experiments were made first to examine the influence of ice embedding on brine rejection and wind-induced Ekman pumping for idealized 2-D and 3-D cases and second to estimate the role of lateral mixing during periods of rapid ice melting that occurred in the Arctic Ocean in September 2007 and 2012, respectively. For the 2-D brine rejection problem, if ice embedding is considered, the results show that during the period of ice formation, the water tends to be less stratified due to enhanced vertical mixing and the two-layer flow feature over the shelf could be replaced by homogenous flow. After the shelf was fully occupied by ice, the dense water formation and offshore transport over the slope could be greatly decreased as the injection of high salinity water is ceased. During the period of ice melting, lateral heating makes ice melt faster, leading to a larger cross-shelf sea level gradient and thus a strong along-shelf flow over the shelf. For the 3-D Ekman pumping problem driven by a clockwise wind stress curl over a circular basin, the influence of ice-embedding on downward Ekman pumping is small in the case with a flat bottom but significant in the case with slope topography. Wind-induced upwelling over the slope tends to enhance the lateral melting rate, which makes the ice melt faster. In the case with ice embedding, the Ekman pumping rate could be one order of magnitude larger and produce a deeper thermohaline. The real-time simulation in the Arctic Ocean was done using the Arctic Ocean FVCOM (AO-FVCOM) through nesting with the Global-FVCOM. The results show that the melting due to lateral mixing was significantly larger when ice embedding physics are considered.