Evaluation of Sea Ice Deformation and Its Spatial Characteristics from the Regional Arctic System Model.

摘要

The Regional Arctic System Model (RASM) is used to investigate the process and frequency of extreme sea ice shear deformation events resulting in pycnocline upwelling due to Ekman pumping as described in McPhee et al. (2005). RASM is a fully coupled land, atmosphere, sea ice, and ocean model with high spatial and temporal resolution. Time series analysis of the upper ocean temperature structure, basal melt rate, total deformation rate, and ice-ocean stress curl yield the identification of individual events. Shear deformation events generate an upper ocean response given a positive ice-ocean stress curl, i.e., induced by counterclockwise rotation in the ice velocity field relative to the underlying ocean. Spatial and temporal characterization of the total deformation rate indicates that fine spatial and temporal resolution, on a statistical scale, is important for the energy budget of the Arctic. Results demonstrate a power law relationship between the mean deformation rate and length scale. This is hypothesized as being due to RASMs fully coupled system allowing for naturally occurring high frequency noise and the cascade of energy among model components. Simulated events are infrequent and their relative impact on large scale energy exchange remains undetermined, which warrants further research of these phenomena.