Berlin 2012 – wissenschaftliches Programm

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UP: Fachverband Umweltphysik

UP 9: Poster session

UP 9.5: Poster

Mittwoch, 28. März 2012, 18:30–19:15, Poster F

Modeling the morphogenesis of brine channels in sea ice — Silke Thoms¹, •Bernd Kutschan², Klaus Morawetz^2,3, and Sibylle Gemming⁴ — ¹Alfred Wegener Institut, Am Handelshafen 12, D-27570 Bremerhaven, Germany — ²Münster University of Applied Sciences, Stegerwaldstrasse 39, 48565 Steinfurt, Germany — ³International Institute of Physics (IIP) Av. Odilon Gomes de Lima 1722, 59078-400 Natal, Brazil — ⁴Helmholtz-Zentrum Dresden Rossendorf, PF 51 01 19, 01314 Dresden, Germany

The brine channel web in sea ice as biotope for microorganisms acts as an important CO₂ sink of about 18% of the annual primary carbon production in ice-covered Southern Ocean. Two mechanisms of brine channel formations are represented. The structure of ice, the tetrahedricity, and the salinity are identified as coupled order parameters and their evolution equations are derived invoking conservation laws. The stability analysis provides the phase diagram where brine channels can be formed. In thermodynamics the parameters determine the supercooling or superheating region and the specific heat respectively. In contrast to the Turing model the diffusivity does not enter this phase diagram but determines only the structure size. The numerical solution shows a short-time behavior of structure formation where the freezing is assumed and a large-time broadening of the structure. The structure and freezing parameters as well as diffusivity are extracted from experimental values of water and ice. With the help of these realistic parameters the brine channel distribution is calculated and found in agreement with the measured samples.