Structure, Salinity, and Density of Multi-Year Sea Ice Pressure Ridges,"

• Main Authors: J A Richter-Menge, G F N Cox
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1985
• Subjects: Arctic; Beaufort Sea; Sea ice
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1079.4739; http://proceedings.asmedigitalcollection.asme.org/data/Journals/JERTD2/26408/493_1.pdf

Introduction Multi-year pressure ridges present the most significant harzard to arctic offshore structures and vessels. It is therefore surprising that we know so little about their internal physical characteristics. Only recently has a program been initiated to systematically examine the structure and mechanical properties of ice samples taken from multi-year ridges When a pressure ridge is first formed it consists of angular, broken blocks of ice. Initially, the blocks are weakly joined together. During the course of the winter, the ridge begins to consolidate. In the summer, both the top and bottom of the ridge undergo ablation and become rounded in appearance. Meltwater permeates the ridge, flowing into void spaces. If the ridge survives the summer melt and is present the following winter it is called a multi-year ridge. At this point the ridge is massive, with few or no voids, and has a characteristic low salinity. On the surface of the ridge, individual blocks of ice are no longer discernible. Instead, the ridge is rounded, with an irregular pattern of height variations. A split ridge will reveal that the internal structure of the ridge still maintains its blocky nature. This history of formation can result in large variations of the ice type and crystal orientation in ice samples taken from a multi-year ridge. In this paper data are given on the variation of ice structure, salinity, and density observed in ice taken from multi-year ridges located in the Alaskan Beaufort Sea. While the mechanical testing of individual multi-year ridge samples provides important strength parameters, we must understand how to apply the results on a larger scale. This requires information on the internal composition of multi-year ridges. We should pay particularly close attention to the amount of columnar ice in the ridges studied and the orientation of the