  Brine channels are formed in sea ice under certain constraints and represent
a habitat of different microorganisms. The complex system depends on a number
of various quantities as salinity, density, pH-value or temperature. Each
quantity governs the process of brine channel formation. There exists a strong
link between bulk salinity and the presence of brine drainage channels in
growing ice with respect to both the horizontal and vertical planes. We develop
a suitable phenomenological model for the formation of brine channels both
referring to the Ginzburg-Landau-theory of phase transitions as well as to the
chemical basis of morphogenesis according to Turing. It is possible to conclude
from the critical wavenumber on the size of the structure and the critical
parameters. The theoretically deduced transition rates have the same magnitude
as the experimental values. The model creates channels of similar size as
observed experimentally. An extension of the model towards channels with
different sizes is possible. The microstructure of ice determines the albedo
feedback and plays therefore an important role for large-scale global
circulation models (GCMs).
