NEWS
2025-11-18
Eddies Trap Sea Ice in the Marginal Ice Zone: New Study Reveals How Ocean Dynamics Shape Polar Ice Patterns
Editor: Yongqing CAI (Polar Research Institute of China)
The marginal ice zone (MIZ)—the dynamic boundary where sea ice meets the open ocean—is one of the most complex and rapidly changing regions in the polar seas. In this transition zone, sea ice is constantly influenced by oceanic waves, eddies, and fronts, leading to strong spatial variability and temporal evolution. Beyond its local importance, the MIZ plays a crucial role in the global climate system by regulating the exchange of heat, freshwater, and momentum between the atmosphere, ocean, and ice. It is also a hotspot of biological productivity, shaping ocean circulation, climate feedbacks, and polar ecosystems.
Understanding the physical processes in the MIZ is essential for improving predictions of polar climate change. However, the region’s abundance of small- and mesoscale oceanic structures—such as fronts and eddies (Figure 1)—remains poorly represented in current climate models, introducing major uncertainties in projections of sea ice evolution. To address this challenge, researchers from the Polar Research Institute of China, have conducted a series of high-resolution numerical simulations to investigate how eddies interact with sea ice at the ice edge.
The study reveals that sea ice accumulation patterns are closely tied to the development of ocean eddies generated by frontal instabilities. During the early stage of frontogenesis, when eddies are relatively small, sea ice tends to cluster within cyclonic eddies—primarily due to Ekman-driven surface convergence that promotes ice gathering. As the instability evolves, larger-scale eddy dipoles emerge and detach from the original front, transporting fresher surface waters from the light to the dense side of the front. In this stage, sea ice accumulation shifts to the anticyclonic component of the eddy pair (Figure 2), where local convergence arises from frontal dynamics rather than Ekman effects.
The researchers found that this anticyclonic trapping of sea ice is particularly pronounced under conditions of low ice concentration. Moreover, as the accumulated sea ice melts, it releases freshwater into the upper ocean, enhancing stratification and modifying the surface density and flow structure. This feedback not only regulates the growth of eddy dipoles but also alters subsequent sea ice aggregation patterns.
“These results highlight the pivotal role of mesoscale and submesoscale eddies in controlling how sea ice moves, melts, and interacts with the ocean,” said the study’s authors. “Our findings provide new insight into the coupled ice–ocean dynamics of the marginal ice zone and offer a pathway to improve the representation of these processes in climate models.”
By uncovering how eddies trap and redistribute sea ice within the MIZ, this research advances our understanding of the physical mechanisms driving polar ice variability. It also underscores the importance of resolving fine-scale ocean dynamics to more accurately predict the response of sea ice to global warming and its feedbacks on the Earth’s climate system.
Reference:
Cai, Y., Lei, R., Chen, D., du Plessis, M., Liu, C., Han, X., & Wu, L. (2025). Anticyclonic component of eddy dipoles traps sea ice within the marginal ice zone. Journal of Geophysical Research: Oceans, 130, e2025JC022426. https://doi.org/10. 1029/2025JC022426
Figure 1 Snapshot of SAR imagery (https://www.polarview.aq/antarctic)
Figure 2 The evolution of front instabilities interact with the mobile sea ice in MIZ in the control simulation