Noa Kraitzman

Through its role as an interface between ocean and atmosphere, sea ice is important both physically and biologically. We propose here that the resident microbial community can influence the structure of sea ice, particularly near its ocean interface, by effectively lowering the local freezing point via an osmolytic mechanism. This lowered freezing point can enhance fluid flow, linking a bottom, convective ice layer with the underlying ocean, resulting in improved nutrient uptake and byproduct removal. A mathematical model based on a previously suggested abiotic one dimensional simplification of mushy ice fluid dynamics is used to illustrate, and supporting measurements of freezing point depression by lab grown sea ice-associated organisms are provided.

Through its role as a an interface between ocean and atmosphere, sea ice is important both physically and biologically. We propose here that the resident microbial community can influence the structure of sea ice, particularly near its ocean interface, by effectively lowering the local freezing point via an osmolytic mechanism. The lower freezing point can enhance fluid flow, linking a bottom, convective ice layer with the underlying ocean, resulting in improved nutrient uptake and byproduct removal. A mathematical model based on a previously suggested abiotic one dimensional simplification of mushy ice fluid dynamics is used to illustrate, and supporting measurements of freezing point depression by lab grown sea ice-associated organisms are provided.

Through its role as a an interface between ocean and atmosphere, sea ice is important both physically and biologically. We propose here that the resident microbial community can influence the structure of sea ice, particularly near its ocean interface, by effectively lowering the local freezing point via an osmolytic mechanism. The lower freezing point can enhance fluid flow, linking a bottom, convective ice layer with the underlying ocean, resulting in improved nutrient uptake and byproduct removal. A mathematical model based on a previously suggested abiotic one dimensional simplification of mushy ice fluid dynamics is used to illustrate, and supporting measurements of freezing point depression by lab grown sea ice-associated organisms are provided.

Through its role as a an interface between ocean and atmosphere, sea ice is important both physically and biologically. We propose here that the resident microbial community can influence the structure of sea ice, particularly near its ocean interface, by effectively lowering the local freezing point via an osmolytic mechanism. The lower freezing point can enhance fluid flow, linking a bottom, convective ice layer with the underlying ocean, resulting in improved nutrient uptake and byproduct removal. A mathematical model based on a previously suggested abiotic one dimensional simplification of mushy ice fluid dynamics is used to illustrate, and supporting measurements of freezing point depression by lab grown sea ice-associated organisms are provided.

Through its role as a an interface between ocean and atmosphere, sea ice is important both physically and biologically. We propose here that the resident microbial community can influence the structure of sea ice, particularly near its ocean interface, by effectively lowering the local freezing point via an osmolytic mechanism. The lower freezing point can enhance fluid flow, linking a bottom, convective ice layer with the underlying ocean, resulting in improved nutrient uptake and byproduct removal. A mathematical model based on a previously suggested abiotic one dimensional simplification of mushy ice fluid dynamics is used to illustrate, and supporting measurements of freezing point depression by lab grown sea ice-associated organisms are provided.

Through its role as a an interface between ocean and atmosphere, sea ice is important both physically and biologically. We propose here that the resident microbial community can influence the structure of sea ice, particularly near its ocean interface, by effectively lowering the local freezing point via an osmolytic mechanism. The lower freezing point can enhance fluid flow, linking a bottom, convective ice layer with the underlying ocean, resulting in improved nutrient uptake and byproduct removal. A mathematical model based on a previously suggested abiotic one dimensional simplification of mushy ice fluid dynamics is used to illustrate, and supporting measurements of freezing point depression by lab grown sea ice-associated organisms are provided.

Sea ice regulates heat exchange between the ocean and atmosphere in Earth’s polar regions. The thermal conductivity of sea ice governs this exchange, and is a key parameter in climate modelling. However, it is challenging to measure and predict due to its sensitive dependence on temperature, salinity and brine microstructure. Moreover, as temperature increases, sea ice becomes permeable, and fluid can flow through the porous microstructure. While models for thermal diffusion through sea ice have been obtained, advective contributions to transport have not been considered theoretically. Here, we homogenize a multiscale advection–diffusion equation that models thermal transport through porous sea ice when fluid flow is present. We consider two-dimensional models of convective flow and use an integral representation to derive bounds on the thermal conductivity as a function of the Péclet number. These bounds guarantee enhancement in the thermal conductivity due to the added flow. Further, we relate the Péclet number to temperature, making these bounds useful for global climate models. Our analytic approach offers a mathematical theory which can not only improve predictions of atmosphere–ice–ocean heat exchanges in climate models, but can provide a theoretical framework for a range of problems involving advection–diffusion processes in various fields of application.

A holistic review is given of the Southern Ocean dynamic system, in the context of the crucial role it plays in the global climate and the profound changes it is experiencing. The review focuses on connections between different components of the Southern Ocean dynamic system, drawing together contemporary perspectives from different research communities, with the objective of closing loops in our understanding of the complex network of feedbacks in the overall system. The review is targeted at researchers in Southern Ocean physical science with the ambition of broadening their knowledge beyond their specific field, and aims at facilitating better‐informed interdisciplinary collaborations. For the purposes of this review, the Southern Ocean dynamic system is divided into four main components: large‐scale circulation; cryosphere; turbulence; and gravity waves. Overviews are given of the key dynamical phenomena for each component, before describing the linkages between the components. The reviews are complemented by an overview of observed Southern Ocean trends and future climate projections. Priority research areas are identified to close remaining loops in our understanding of the Southern Ocean system.

We derive a thermodynamically consistent model for liquid-solid phase change in sea ice by incorporating a phase sensitive scalar to a classical framework of liquid-solid phase change. The entropy ...