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Granular flow in the marginal ice zone
1Department of Space and Climate Physics, Centre for Polar Observation and Modelling, University College London, UK. dlf@mssl.ucl.ac.uk
Summary
This study reveals that the granular nature of sea ice, not ocean currents, naturally explains the formation of the ice jet in the marginal ice zone (MIZ). This granular rheology is key to understanding MIZ dynamics.
Area of Science:
- Oceanography
- Sea Ice Physics
- Geophysics
Background:
- The marginal ice zone (MIZ) dynamics are complex due to ocean waves, atmospheric/oceanic gradients, and sea ice rheology.
- Previous models often attributed the MIZ ice jet to underlying ocean currents.
Purpose of the Study:
- To investigate the role of sea ice rheology in determining MIZ dynamics.
- To demonstrate that sea ice's granular nature can explain the formation of the ice jet.
Main Methods:
- Sea ice is modeled as a granular material with composite rheology (collisional and plastic interactions).
- A simplified MIZ model incorporating momentum balance and fluctuation kinetic energy balance was developed.
- Steady-state solutions were derived using elementary methods.
Main Results:
- The model predicts a concentrated region of rapid ice flow parallel to the ice edge, known as the ice jet.
- This ice jet emerges as a natural consequence of the sea ice's granular properties.
- The findings challenge previous explanations that relied solely on ocean currents.
Conclusions:
- Sea ice rheology, specifically its granular characteristics, is a primary driver of MIZ dynamics.
- The granular model provides a more fundamental explanation for the observed ice jet phenomenon.
- This research offers new insights into the physical processes governing the MIZ.
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