Short‐term ice motion modeling with application to the Beaufort Sea

Abstract

A short‐term, small‐scale ice motion model was developed in order to facilitate the comparison of various conceptual and numerical formulations. This ice motion model is comprised of two basic components: a momentum balance or equation of motion component and a thickness distribution component. The equation of motion component includes the standard terms relating to air stress, water stress, Coriolis force, sea surface tilt, and internal ice stress. In order to describe the internal ice stress, three different constitutive laws were implemented: a standard linear viscous constitutive law, a closed‐form viscous plastic constitutive law, and a piecewise linearized viscous plastic constitutive law. For the thickness distribution component, a choice of either a two‐level or a multicategory model may be used to characterize the spatial and temporal changes in the thickness distribution of the ice cover. The governing equations for both of these basic ice motion model components are presented. The finite element method based on the Galerkin method of weighted residuals is used to spatially integrate the resulting set of nonlinear partial differential equations while a standard recurrence relation is employed for the temporal integration. The selection of an Eulerian or Lagrangian description for both the equations of motion and the thickness distribution equations is also included in the model development. In order to investigate the response of the developed ice motion model and its various options, the model was applied to a 4‐day ice motion episode in the southern Beaufort Sea. The response of the ice motion model was quantified in terms of the magnitude and the spread of the difference between calculated and observed ice displacements. Comparison between the various model options is included and their effect on the overall model performance is discussed.

Sensitivity and uncertainty analysis of a short‐term sea ice motion model

“…A detailed description of the various ice velocity simulations for this period is presented by Thomson et al [1988]. The general ice motion during this period was predominately onshore, from the northwest.…”

“…The first component consists of a momentum balance equation which accounts for the transfer of momentum to the ice pack from external sources (i.e., wind and ocean currents). The generally agreed form [Thomson et al, 1988;Coon, 1980;Hibler, 1979] of this component for in-plane motion over a distance of several hundred kilometers and a period of 3 or 4 days may be written as 0U m --= -mu-Vu -mfc• x (u -Uw) Ot…”

“…To simulate the ice motion over this 4-day study period, the short-term ice motion model developed by Thomson et al [1988] was used. The spatial domain was discretized into 184 nodes and 164 elements as shown in Figure 4.…”

“…A number of short-term ice motion models have been developed in order to forecast small-scale ice motion [e.g., Thomson et al, 1988;Leppiiranta, 1981;Pritchard et al, 1977]. Due to the complex nature of the governing equations which constitute these models, no available analytical solution exists, and therefore numerical techniques such as the finite element method and the finite difference method are utilized.…”

A finite element sea ice model of the Canadian Arctic Archipelago

“…Other studies followed (e.g. Becker 1976;Sodhi and Hiber 1980;Thomson et al 1988). Recently, two FEM models were introduced: a sea ice model coupled to a simple slab ocean (Lietaer et al 2008) and FESOM, a coupled seaice-ocean model ).…”