the region covered by sea ice, typically given in square kilometers. For a grid cell, it is the area of the portion of the cell covered by ice. For an entire hemisphere, it is the total area covered by ice, which corresponds to sum of the area of each cell multiplied by the fractional concentration for that cell.
the thickness at which ice no longer grows because it is so thick that heat from the ocean can no longer be conducted through the ice; it may take several years of growth and melt for ice to reach an equilibrium thickness.