The Polar Ice Prediction System version of the Hibler ice model [Preller and Posey, 1989> has been modified into spherical coordinates and extended to include most of the sea ice-covered areas in the northern hemisphere. The earth-orientated longitudes and latitudes have been transformed into a spherical geometry in which the new ''equator'' coincides with the 10¿E--170¿W great circle and the new ''north pole'' is located at the intersection of the 100¿E meridian and the equator. The coordinate transformation is required to avoid a numerical singularity at the north pole and numerical instabilities in high latitudes. The Cox ocean model [1984> is also transformed into the new coordinate system and coupled with the sea ice model. Monthly atmospheric forcing for 1986 from the Naval Operational Global Atmospheric Prediction System has been used to drive the spherical coordinate version of the ice-ocean coupled model. The estimated ice thickness distribution shows that the thickest ice is located along the northern coasts of Canada, and the ice gradually becomes thinner across the Arctic ocean toward the Soviet coast. The average ice thickness is about 3.5 m for March 1986 in the Arctic basin and can vary from open water up to 6 m or thicker, depending on location and seasons. The modeled ice edge location is consistent in general with ice data from the Navy-NOAA Joint Ice Center. River runoff is not included in this coupled model and may affect the ice growth in the Yellow Sea and the Baltic Sea in winter. ¿ American Geophysical Union 1992