Contemporaneous field measurements of pack ice stress and ice strain measurements from SAR imagery

Material constitutive laws are commonly developed from stress/strain data which are obtained from laboratory measurements; e.g., a sample of the material is stressed in a load machine, and the resulting deformation is measured. Similarly, developing or verifying a constitutive law for polar pack ice is best done by obtaining contemporaneous ice stress and strain measurements. A pilot program to measure these parameters was performed during April 1992 in the southern Beaufort Sea. Directional stress was measured at two locations by gauges imbedded in the sea ice. Strain was obtained from sequential ERS-1 satellite synthetic aperture radar (SAR) images (typically three days apart). Unfortunately, no significant ice stress or ice motion events occurred during the brief measurement period. However, a failure (yield) envelope for thick ice, based on ice stress measurements taken in the eastern Arctic Ocean, was developed. These pilot studies verified the techniques to be used during an eight-month measurement program which will take place in the Beaufort Sea during the 1993-1994 ice season