Testing of a coupled ice-ocean model in a sea ice forecasting system

The Naval Research Laboratory has developed a coupled ice-ocean model which covers most of the sea ice-covered regions of the Northern Hemisphere. This model was designed to replace the three existing Navy sea ice forecast systems: the Polar Ice Prediction System (PIPS) and the two regional systems, the Polar Ice Prediction System-Barents Sea (RPIPS-B)-and the Polar Ice Prediction System-Greenland Sea (RPIPS-G). These systems forecast over the central Arctic, Barents Sea and Greenland Sea (PIPS) and then at higher resolution over the Barents Sea (RPIPS-B) and over the Greenland Sea (RPIPS-G). The coupled ice-ocean model, the Polar Ice Prediction System 2.0 (PIPS2.0), covers all of these regions and the remaining ice-covered marginal seas of the northern hemisphere at a resolution comparable to the two existing regional forecast systems. PIPS2.0 is scheduled to replace the existing forecast systems in 1994. The coupled ice-ocean model consists of the Hibler ice model and the Cox ocean model. The Hibler ice model has been rewritten in spherical coordinates to both be consistent with the Cox ocean model and to define a more realistic grid at lower latitudes. In addition, both models are applied on a rotated coordinate system. This new coordinate system has the intersection of the 100°E meridian and the equator as the new “North Pole”. This new coordinate system was applied to remove the numerical singularity which will occur at the North Pole in a spherical coordinate system. The model domain extends from the pole to approximately 30°N latitude and includes marginal seas such as the Sea of Okhotsk, the Sea of Japan and the Yellow Sea in the Pacific and the Gulf of St. Lawrence and the Labrador Sea in the Atlantic