Development of a Constitutive Law for a 5-15 Km Scale in the Arctic Ice Pack
Abstract
LONG TERM GOALS. Develop a basis for relating differential pack ice motion to the resulting stress variations within floes on scales of the order of 5-15 km. Use such relationships to develop a constitutive law relating strains to stresses in pack ice to be utilized in the next generation, high resolution, forecasting models for high latitude regions. OBJECTIVES. Study motion-induced stresses in pack ice through the analyses of a variety of observations collected during the Sea Ice Mechanics Initiative. Investigate the relationships between observed differential ice motion over the scales of 5-15 km and the observed residual (internal) stresses within floes in an attempt to develop a rheology relating strain in the ice pack to internal stresses within individual floes. APPROACH. To directly assess the mechanical behavior of the Arctic pack ice at regional scales, the Office of Naval Research (ONR) initiated a program of concurrent measurements of in-situ ice stresses and ice motion during the recent Sea Ice Mechanics Initiative (SIMI). A stress and deformation array was established over a 20 km region of the pack ice in the Alaskan Beaufort Sea, and measurements were recorded over six months, beginning in September 1993. To develop a more detailed understanding of the relationship between observed stresses and ice pack deformation, we focused on the characteristics of the observed motion-induced stresses. Since stresses in a floe result from both thermal as well as motion-induced processes, a technique had to be developed to estimate those stresses due strictly to ice motion. With a satisfactory estimate of the motion-induced stresses in hand, a number of techniques was used to develop an understanding of how these stresses are generated. These techniques include a comparison of the measured stresses to those stresses determined as residuals from a force-balance analysis using SIMI wind, under-ice current, and ice motion data.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 30, 1997
- Accession Number
- ADA635929
Entities
People
- James K. Lewis