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Environmental Modeling Center


About the NCEP Ice Drift Model

This model uses a simple drift law relation to predict the displacement of an ice floe (if one is present) from a present location through time. In the northern hemisphere, the law is the Thorndike and Colony [1982]. In the southern hemisphere, the law is Martinson and Wamser [1990]. The points in the northern hemisphere are defined on a fixed grid (the Skiles points) and along the ice edge from the most recent US National Ice Center (NIC) ice edge analysis. In the southern hemisphere, the points are only from the NIC analysis. The Skiles points locations are given in the file forecast.points, available by anonymous ftp to, directory pub/ice/support None of these points are on the Great Lakes, as the appropriate drift law for them is certainly different than for the Arctic.

The forecasts (model guidance) are made each day, for each forecast day out to day 16. The guidance consists of the drift direction (in meteorological convention) and distance in nautical miles for each point.  The model output displayed graphically on the web gives the drift distance in nautical miles, and the ice drifts along the black bar towards the red dot.

This model was approved for operations 11/1995, and implemented 10/1997. Operational output is available at This includes graphics of the model output for the Alaska Region.

A complete description of the model and of its forecast verification is available in postscript format at http:///mmab/papers/tn114.

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Page last modified: Friday, 03-Jan-2014 19:16:00 UTC