Open AccessLaboratory tests on ridging and rafting of ice sheets
Author(s) -
Tuhkuri Jukka,
Lensu Mikko
Publication year - 2002
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2001jc000848
Subject(s) - geology , ridge , sea ice , ice sheet , mineralogy , geomorphology , climatology , paleontology
The mechanical deformation of a sea ice cover takes place through ridging and rafting. These processes have been studied in an ice basin by pushing two identical ice sheets together. Nonuniform ice sheets consisting of floes of thickness t 1 and thin ice of thickness t 2 connecting the floes were used. The major thickness t 1 and the thickness ratio t 2 / t 1 were varied. Ice sheets of uniform thickness ( t 2 / t 1 = 1) never formed ridges; they only rafted. However, when ice sheets of nonuniform thickness were used, initial rafting transformed into ridging. In general, high values of t 1 and low values for t 2 / t 1 favored ridging, while low values of t 1 and high values for t 2 / t 1 favored rafting. The forces during the tests were measured. During the initial rafting stage the force increased linearly with displacement. The experiments also suggest that the ridging force has a maximum value. This limit can be related to horizontal growth of the ridge or onset of ridging in another site. The relation between force and ice sheet thickness has also been analyzed. Further, from the force and the measured ridge profiles it was possible to estimate the ratio of work to change in potential energy. This ratio was about 15 for ridging and about 35 for rafting.