Response of Dry and Floating Saline Ice to Cyclic Compression

• Published in: Geophysical research letters 2022-08, Vol.49 (15), p.n/a
• Main Authors: Wei, Mingdong, Prasanna, Malith, Cole, David M., Polojärvi, Arttu
• Format: Article
• Language: English
• Subjects: Chemical analysis; Climate; Climate change; Compression; Cyclic loading; Cyclic loads; Deformation; Density; Dislocation density; Energy dissipation; Energy exchange; Experimentation; Experiments; Fieldwork; Floating ice; Future climates; Laboratories; Laboratory experimentation; Laboratory experiments; Mechanical properties; Ocean waves; Physics; Rheological properties; Rheology; Sea ice; Seawater; Temperature gradients; Unloading; Water analysis; Wave period
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2022GL099457

Laboratory experiments on saline ice are often performed on cold, isothermal and dry specimens out of convenience versus working with warm specimens or specimens floating in water. The laboratory conditions, thus, usually involve non‐natural conditions. This study compares cyclic loading experiments covering the main range of ocean wave periods performed on both dry, isothermal and warm, floating ice specimens. Results indicate that −2.5°C isothermal dry specimens have higher moduli than floating specimens with an average temperature of −2.5°C with a naturally occurring temperature gradient. Moreover, the dislocation density estimated using a physics‐based model and the strain energy density dissipated in 10−3–10−2 Hz loading‐unloading cycles are much lower for the −2.5°C dry specimens than for the −2.5°C floating specimens. Although the precise reason for the dislocation density difference requires further study, the results nonetheless contribute to the understanding and implementation of ice rheology and related geophysical modeling. Plain Language Summary Reliable measurements on ice are the cornerstone for accurately simulating the mechanical behavior and dynamics of sea ice. Such simulations are crucial for our predictions of sea ice behavior now and under future climate changes. In laboratory experiments, saline ice specimens are often tested without having them floating on water, whereas in nature, practically all sea ice is floating. Even in fieldwork, sea ice specimens are often taken out of the seawater for testing. It is of interest to quantify how the mechanical behavior of ice changes when specimens are taken from their natural setting. This study finds that the deformation and energy dissipation of dry, isothermal saline ice specimens under cyclic compression are significantly lower than floating ice specimens, even if their average temperatures are equal. This finding calls for more attention to be paid to performing experimentation on ice under more natural conditions in order to gain reliable insight into its mechanical behavior. Key Points The viscoelastic behavior of saline ice under cyclic loading covering the main range of ocean wave periods is examined and modeled Dry, isothermal ice has less viscosity and anelasticity than floating ice of the same average temperature but with a temperature gradient Results contribute to the understanding of in‐situ versus laboratory ice rheology and related geophysical modeling