Three-dimensional modelling study reveals new insights into circulation in ice-covered lakes

A new study, co-authored by iC3 researcher Tore Hatterman, models circulation in ice-covered lakes, potentially opening doors to better understanding the cycling of nutrients and greenhouse gasses in these lake systems. 

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Image: Cross-section of vertical velocity magnitudes in a 75 m deep domain for a lake width of a 2 km and b 40 km. Positive velocity direction is upward. Credit: Environmental Fluid Mechanics (Sharifi et al., 2025).

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Circulation in Ice-Covered Lakes

The study aims to better understand circulation patterns in ice-covered lakes with different temperature layers. These lakes are often thought to exist in a relatively still state due to the absence of external forces that drive circulation, such as wind shear and solar radiation. However, theoretical studies have investigated the potential generation of flow due to interactions between density, gravity, diffusivity, and the slope at the bottom of the lake. In technical terms: diffusion-gravity flows. 

While laboratory studies have been conducted on these flows, little is known about how they might occur in the natural environment. Hattermann and his colleagues aimed to address that knowledge gap in this study.

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Modelling Approach

The models generated in this study were run on an altered version of the Regional Ocean Modeling System (ROMS), which is a three-dimensional model considering flow, mass, and heat transport. 

The model examined the effect of the bottom slope of the lake on flow generation, in addition to other factors such as stored heat from lake sediments and Earth’s rotation (the Coriolis effect). 

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Study Findings

The study found that the modeled results generally agreed with theoretical predictions of the flow. The model identified a minimum slope of the lake bottom that is required for the generation of flow as a function of density differences and lake depth.

When no heat is given off by the lake sediments, the residual circulation from diffusion-gravity flows can overturn the entire water column in 1 to 6 months, depending on lake size. 

The influence of lake sediment heat fluxes can create complex circulation patterns, which are further influenced by the Coriolis effect in all lakes except the smallest ones simulated. 

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What are the implications of this study?

This model study can allow us to better understand the circulation patterns in ice-covered lakes, and to predict how these patterns might respond to climate change and other environmental factors.

Diffusion-driven circulation likely plays a role in regulating biochemical processes at the water-sediment interface by promoting mixing, and transportation heat, nutrients, and oxygen throughout the water column. Modelling work sets the stage for further studies in real lakes researching biochemical cycling.

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The study “Three-dimensional modeling of diffusion-gravity flows in ice covered lakes” is available open access in Environmental Fluid Mechanics.

Tore Hattermann is a researcher in the iC3 Polar Research Hub and the Norwegian Polar Institute (NPI) specializing in polar ice-ocean interactions. He welcomes enquiries from researchers who want to apply for an MSCA postdoctoral fellowship with him this year. Read his interview here.

This blog was written by Jamie Hollander, Fulbright Norway Research Grantee at the UiT Arctic University of Norway, Tromsø. She is currently based in the Geosciences Department, where she contributes to the iC3-affiliated METHANICE and GlaciGas projects and pursues science outreach in Tromsø. She recently received a bachelor’s degree in Earth and Climate Sciences and looks forward to a long career in geoscience research.