Congelation ice formation direction

I took a bit of time to understand this phenomena. Once I understood it, it became really interesting to me since I was working on boundary layer computations in my masters.  Before describing the phenomena let me describe some keywords that would make it easier to understand it.

Congelation ice: This is the ice that grows by freezing in to an existing ice bottom that has already formed in a calm sea.

c-axis: It's the reference axis perpendicular to the plane of a movement of rock or minerals

boundary layer: the fluid layer adjacent to a solid.

corrugated:  a series of parallel ridges and furrows- The free dictionary

Corrugated ice

According to the observations of Langhorne, there seems to be a correlation between the ice formarion direction and the direction of the current. Let's consider the following two figures.

(a) current direction is perpendicular to the grooves parallel to C axis

(b) current direction is perpendicular to the c-axis and parallel to grooves

In the figure (a) current direction is perpendicular to the grooves. This creates mixing in the boundary layer  between the ice and the water. The boundary layer is slightly turbulent. We can also assume that the salinity of this boundary layer is quite high since freezing emits the brine in to the water. The mixing in the boundary layer changes the salinity in figure (a) that makes it more favorable in ice growth. In figure (b) since the groves are aligned with the current direction, we could assume that the boundary layer is laminar and therefore no mixing takes place. It isn't favorable for ice growing. Therefore we  can conclude that ice growing has a tendency to align the c axis parallel to that of the current direction.

Reference: 

Ice in the ocean, Peter Wadhams