A redistribution function of compactness is obtained for a dynamic model of sea ice on the assumption that the work done by the internal stress of sea ice is used to pile up to the sea ice and to reduce its compactness. Supposing that the yield curve has an elliptical form and the stress is a function of strain rate, the redistribution function obtained in the present study is written in the following form: &PSgr;(&egr;1,&egr;2)=F(A)*<(&egr;1+&egr;2)- {(&egr;1+&egr;2)2+(&egr;1-&egr;2)2}1/2> where F(A) is a function of compactness A, and &egr;˙1 and &egr;˙2 are principal components of the strain rate tensor. When this redistribution function was applied to the model proposed by Hibler (1979), calculated ice velocity and ice growth increased up to 50%. ¿ American Geophysical Union 1990