The atmosphere, land, and sea ice components communicate every 30 min whereas the ocean component is coupled with atmosphere once a day. (link.springer.com)
Briegleb, B.P., et al., 2004: Scientific Description of the Sea Ice Component in the Community Climate System Model, Version Three. (ipcc.ch)
The relatively slow progress can partially be explained by the fact that improving sea ice simulation requires improvements in both the atmosphere and ocean components in addition to the sea ice component itself. (ipcc.ch)