Formation of brine channels in sea ice

• Applicant: Professor Dr. Klaus Morawetz
• Subject Area: Oceanography
• Term: from 2011 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 198628513

Within this interdisciplinary project the formation of brine channels in sea ice will be explored. The microscopic properties of sea ice, especially the permeability plays an important role for the energy exchange between ocean and atmosphere and is determined by the brine channel volume. The brine channel structure will be measured by computer tomography and image analysis. We intend to describe the channel structure by two phenomenological models, a morphogenesis approach of Alan Turing in connection with the phase transition theory of Ginzburg and Landau, and the phase field method with respect to the Cahn-Hilliard equation. We solve these nonlinear evolution equations in two and three dimensions and compare the size and texture of the brine channels with the measurements. In addition to the phenomenological equations we support our studies with molecular dynamics simulations and the density functional theory in order to obtain deeper insights at the molecular scale. Comparative first-principles studies will then enhance the trust in the extracted parameters and will lead to classical density functionals for the two phases. We will discuss the phase transitions in terms of a phenomenological theory based on microscopic parameters and try to extract the underlying mechanism for the formation of water-ice boundaries. Specifically, we want to explore three theoretical questions: (i) How are ice-water melting fronts moving, (ii) How are brine channels formed and (iii) How do surface properties influence the structure formation of brine channels. The project is based on the experiences of three fields, the theoretical biological physics, chemical physics and the many-body theory. The final aim of the project is to provide input parameters for global climate models.

• DFG Programme: Infrastructure Priority Programmes
• Subproject of: SPP 1158: Infrastructure area - Antarctic Research with Comparative Investigations in Arctic Sea Ice Areas
• International Connection: Norway
• Participating Persons: Privatdozent Dr. Gerhard Dieckmann; Professorin Dr. Sibylle Gemming; Dr. Sebastian Gerland; Dr. Mats Granskog; Professorin Dr. Nalân Koç; Silke Thoms, Ph.D.